Question

5. Which set of side lengths can be used to form a right triangle?

A. 11, 16, 20
B. 8, 15, 17
C. 6,8,9
D. 6, 15, 17

Answer 1

B

Explanation:

using the converse of Pythagoras' identity

if the longest of the 3 sides is equal to the sum of the squares on the other 2 sides then the triangle is right.

A

longest = 20 → 20² = 400

11² + 16² = 121 + 256 = 377

400 ≠ 377 , so triangle is not right

B

longest = 17 → 17² = 289

8² + 15² = 64 + 225 = 289

then this triangle is right

C

longest = 9 → 9² = 81

6² + 8² = 36 + 64 = 100

81 ≠ 100 , so this triangle is not right

D

longest = 17 → 17² = 289

6² + 15² = 36 + 225 = 261

289 ≠ 261 , so this triangle is not right