Triangles
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SAT Math › Triangles
What is the area of a square that has a diagonal whose endpoints in the coordinate plane are located at (-8, 6) and (2, -4)?
100
100√2
50√2
50
200√2
Explanation
A right triangle has legs of 15m and 20m. What is the length of the hypotenuse?
30m
45m
35m
40m
25m
Explanation
The Pythagorean theorem is a2 + b2 = c2, where a and b are legs of the right triangle, and c is the hypotenuse.
(15)2 + (20)2 = c2 so c2 = 625. Take the square root to get c = 25m
Solve each problem and decide which is the best of the choices given.
If , what is
?
Explanation
This is a triangle. We can find the value of the other leg by using the Pythagorean Theorem.
Remembering that
.
Thus,
.
If , you know the adjacent side is
.
Thus, making
because tangent is opposite/adjacent.
Two sides of a given triangle are both . If one angle of the triangle is a right angle, then what is the measure of the hypotenuse?
Explanation
If we know two sides are equal to and we know that one of the angles is a right angle, then that means that this must be a Special Right Triangle where the interior angles are
.
With this special triangle, we also know that the measure of the hypotenuse is equal to the measure of one side of the triangle times the square root of that measure.
Since one leg of the triangle is . then the hypotenuse is equal to
.
We could also solve this using the Pythagorean Theorem, like so:
What is the hypotenuse of a right triangle with side lengths and
?
Explanation
The Pythagorean Theorem states that . This question gives us the values of
and
, and asks us to solve for
.
Take and
and plug them into the equation as
and
:
Now we can start solving for :
The length of the hypotenuse is .

What is the perimeter of the triangle above?
Explanation
The figure shows a right triangle. The acute angles of a right triangle have measures whose sum is , so
Substituting for
:
This makes a 45-45-90 triangle. By the 45-45-90 Triangle Theorem, the length of leg
is equal to that of hypotenuse
, the length of which is 12, divided by
. Therefore,
Rationalize the denominator by multiplying both halves of the fraction by :
By the same reasoning, .
The perimeter of the triangle is
The base angle of an isosceles triangle is 15 less than three times the vertex angle. What is the vertex angle?
Explanation
Every triangle contains 180 degrees. An isosceles triangle has one vertex angle and two congruent base angles.
Let = vertex angle and
= base angle
So the equation to solve becomes .
What is the area of a square that has a diagonal whose endpoints in the coordinate plane are located at (-8, 6) and (2, -4)?
100
100√2
50√2
50
200√2
Explanation
In order to get to work, Jeff leaves home and drives 4 miles due north, then 3 miles due east, followed by 6 miles due north and, finally, 7 miles due east. What is the straight line distance from Jeff’s work to his home?
2√5
11
10√2
15
6√2
Explanation
Jeff drives a total of 10 miles north and 10 miles east. Using the Pythagorean theorem (a2+b2=c2), the direct route from Jeff’s home to his work can be calculated. 102+102=c2. 200=c2. √200=c. √100√2=c. 10√2=c

In the figure above, is a square and
is three times the length of
. What is the area of
?
Explanation
Assigning the length of ED the value of x, the value of AE will be 3_x_. That makes the entire side AD equal to 4_x_. Since the figure is a square, all four sides will be equal to 4_x_. Also, since the figure is a square, then angle A of triangle ABE is a right angle. That gives triangle ABE sides of 3_x_, 4_x_ and 10. Using the Pythagorean theorem:
(3_x_)2 + (4_x_)2 = 102
9_x_2 + 16_x_2 = 100
25_x_2 = 100
_x_2 = 4
x = 2
With x = 2, each side of the square is 4_x_, or 8. The area of a square is length times width. In this case, that's 8 * 8, which is 64.