Calculating if two acute / obtuse triangles are similar - GMAT Quantitative

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Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

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Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

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Question

.

Order the angles of from least to greatest measure.

Answer

In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .

Corresponding angles of similar triangles are congruent, so, since , .

Therefore, by substitution, .

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Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

Compare your answer with the correct one above

Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

Compare your answer with the correct one above

Question

.

Order the angles of from least to greatest measure.

Answer

In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .

Corresponding angles of similar triangles are congruent, so, since , .

Therefore, by substitution, .

Compare your answer with the correct one above

Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

Compare your answer with the correct one above

Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

Compare your answer with the correct one above

Question

.

Order the angles of from least to greatest measure.

Answer

In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .

Corresponding angles of similar triangles are congruent, so, since , .

Therefore, by substitution, .

Compare your answer with the correct one above

Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

Compare your answer with the correct one above

Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

Compare your answer with the correct one above

Question

.

Order the angles of from least to greatest measure.

Answer

In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .

Corresponding angles of similar triangles are congruent, so, since , .

Therefore, by substitution, .

Compare your answer with the correct one above

Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

Compare your answer with the correct one above

Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

Compare your answer with the correct one above

Question

.

Order the angles of from least to greatest measure.

Answer

In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .

Corresponding angles of similar triangles are congruent, so, since , .

Therefore, by substitution, .

Compare your answer with the correct one above

Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

Compare your answer with the correct one above

Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

Compare your answer with the correct one above

Question

.

Order the angles of from least to greatest measure.

Answer

In a triangle, the angle of greatest measure is opposite the side of greatest measure, and the angle of least measure is opposite the side of least measure. , so their opposite angles are ranked in this order - that is, .

Corresponding angles of similar triangles are congruent, so, since , .

Therefore, by substitution, .

Compare your answer with the correct one above

Question

The triangles are similar. What is the value of x?

Answer

The proportions of corresponding sides of similar triangles must be equal. Therefore, \small \frac{8}{12}\ =\ \frac{10}{x}. \small 8x\ =\ 120; x\ =\ 15.

Compare your answer with the correct one above

Question

is an equilateral triangle. Points are the midpoints of , respectively. is constructed.

All of the following are true except:

Answer

The three sides of are the midsegments of , so is similar to .

By the Triangle Midsegment Theorem, each is parallel to one side of .

By the same theorem, each has length exactly half of that side, giving twice the perimeter of .

But since the sides of have twice the length of those of , the area of , which varies directly as the square of a sidelength, must be four times that of .

The correct choice is the one that asserts that the area of is twice that of .

Compare your answer with the correct one above

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