How to find the perimeter of a 45/45/90 right isosceles triangle

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Geometry › How to find the perimeter of a 45/45/90 right isosceles triangle

Questions 1 - 10
1

What is the perimeter of a right isosceles triangle with leg lengths of ?

Explanation

13

Recall how to find the perimeter of a triangle:

Now, because this is a right isosceles triangle, we know the following:

From the information given in the question, we already have two of the sides needed. Now, recall the Pythagorean Theorem to find the third side of the triangle, the hypotenuse.

The Pythagorean Theorem can then be simplifed to the following equation:

Now, solve for since the question asks for the length of the hypotenuse.

Now, plug in the given value for to find the length of the hypotenuse.

Now that we have all three sides of the triangle, we can find the perimeter. Use a calculator and round to decimal places.

2

Find the perimeter of a triangle with a leg length of cm.

Explanation

In order to solve for the perimter (the sum of all sides), all side lengths must be known.

Because it's been stated the triangle is 45/45/90, this means that it is also isosceles. Therefore, given that one of the leg lengths is 5 cm, this means that the other leg must also be 5 cm. This leaves the hypotenuse as unknown; let's label this as x.

Find_the_perimeter

The third side can be easily determined through the Pythagorean Theorem because it's a right triangle.

, c=x

But because the hypotenuse measures distance, x cannot be a negative number. Therefore, x=5√2.

Now, perimeter can be solved for.

3

What is the perimeter of a right isosceles triangle that has leg lengths of ?

Explanation

13

Recall how to find the perimeter of a triangle:

Now, because this is a right isosceles triangle, we know the following:

From the information given in the question, we already have two of the sides needed. Now, recall the Pythagorean Theorem to find the third side of the triangle, the hypotenuse.

The Pythagorean Theorem can then be simplifed to the following equation:

Now, solve for since the question asks for the length of the hypotenuse.

Now, plug in the given value for to find the length of the hypotenuse.

Now that we have all three sides of the triangle, we can find the perimeter. Use a calculator and round to decimal places.

4

Find the perimeter.

5

Explanation

13

Notice that the given triangle is a right isosceles triangle. The two legs with the tick marks are the same length.

The lengths of the legs in the given triangle are then .

Next, find the length of the hypotenuse by using the Pythagorean Theorem.

Plug in the value of the length of a leg to find the length of the hypotenuse.

Finally, recall how to find the perimeter of a triangle:

Plug in the values for this triangle to find its perimeter.

Make sure to round to two places after the decimal.

5

What is the perimeter of a right isosceles triangle with leg lengths of ?

Explanation

13

Recall how to find the perimeter of a triangle:

Now, because this is a right isosceles triangle, we know the following:

From the information given in the question, we already have two of the sides needed. Now, recall the Pythagorean Theorem to find the third side of the triangle, the hypotenuse.

The Pythagorean Theorem can then be simplifed to the following equation:

Now, solve for since the question asks for the length of the hypotenuse.

Now, plug in the given value for to find the length of the hypotenuse.

Now that we have all three sides of the triangle, we can find the perimeter. Use a calculator and round to decimal places.

6

Find the perimeter.

1

Explanation

13

Notice that the given triangle is a right isosceles triangle. The two legs with the tick marks are the same length.

The lengths of the legs in the given triangle are then .

Next, find the length of the hypotenuse by using the Pythagorean Theorem.

Plug in the value of the length of a leg to find the length of the hypotenuse.

Finally, recall how to find the perimeter of a triangle:

Plug in the values for this triangle to find its perimeter.

Make sure to round to two places after the decimal.

7

An isosceles right triangle has a hypotenuse of 6 centimeters. What is its perimeter?

Explanation

An isoceles right triangle has two congruent legs. We use the Pythagorean Theorem, which states that a2 + b2 = c2, where a and b are the legs and c is the hypotenuse.

Let = leg length.

Because this is an isosceles triangle, the two legs have the same length. Plug this and the hypotenuse length into the Pythagorean Theorem and solve for x:

Thus the perimeter is .

Plug in our value for x:

8

The following image is not to scale.

Find the perimeter of the triangle. Round to the nearest foot.

Finding_the_perimeter

Explanation

Finding_the_perimeter

The problem tells us the triangle is 45/45/90. The goal is to solve for the perimeter, which can be determined through , where the s's are in reference to the three sides and P stands for perimeter.

In the figure, two of the three sides are given. In order to calculate the hypotenuse, two methods are possible:

1. using the Pythagorean Theorem

2. using Find_the_leg_length_resolution

After calculations, the hypotenuse is

Perimeter can be calculated out to be:

9

What is the perimeter of a right isosceles triangle with leg lengths of ?

Explanation

13

Recall how to find the perimeter of a triangle:

Now, because this is a right isosceles triangle, we know the following:

From the information given in the question, we already have two of the sides needed. Now, recall the Pythagorean Theorem to find the third side of the triangle, the hypotenuse.

The Pythagorean Theorem can then be simplifed to the following equation:

Now, solve for since the question asks for the length of the hypotenuse.

Now, plug in the given value for to find the length of the hypotenuse.

Now that we have all three sides of the triangle, we can find the perimeter. Use a calculator and round to decimal places.

10

What is the perimeter of a right isosceles triangle with leg lengths of ?

Explanation

13

Recall how to find the perimeter of a triangle:

Now, because this is a right isosceles triangle, we know the following:

From the information given in the question, we already have two of the sides needed. Now, recall the Pythagorean Theorem to find the third side of the triangle, the hypotenuse.

The Pythagorean Theorem can then be simplifed to the following equation:

Now, solve for since the question asks for the length of the hypotenuse.

Now, plug in the given value for to find the length of the hypotenuse.

Now that we have all three sides of the triangle, we can find the perimeter. Use a calculator and round to decimal places.

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