Test

The angle measures in a triangle are in the ratio 1:3:5. The longest side of the triangle measures 5 inches. What is the approximate perimeter of the triangle?

A. 9.0 in
B. 9.4 in
C. 11.1 in
D. 12.7 in



Answer :

To determine the approximate perimeter of the triangle when the angles are in the ratio 1:3.5 and the longest side measures 5 inches, follow these steps:

1. Understand the Scenario:
- The longest side of the triangle is given as 5 inches.
- The ratio of the side lengths is 1:3.5.

2. Calculate the Scale Factor:
- The length of the longest side (5 inches) corresponds to the side with the largest ratio value.
- The scale factor is obtained by dividing the longest side by the highest value in the ratio (3.5):
- Scale factor = 5 / 3.5
- Scale factor ≈ 1.4285714285714286

3. Determine the Lengths of the Other Sides:
- Using the scale factor, calculate the lengths of the other two sides:
- First side = 1 Scale factor
- First side ≈ 1.4285714285714286 inches
- Second side = 3.5
Scale factor
- Second side = 5 inches (which matches the given longest side, as expected because it was used to derive the scale factor)

4. Calculate the Perimeter:
- The perimeter of the triangle is the sum of all side lengths:
- Perimeter = First side + Second side + Longest side
- Perimeter ≈ 1.4285714285714286 + 5 + 5
- Perimeter ≈ 11.428571428571429 inches

Therefore, the approximate perimeter of the triangle is closest to 11.1 inches. Hence, the correct option is:

11.1 inches