Question

b. What mistake might the student have​ made?
A.
She found the sum of the square roots of the lengths of the legs.
B.
She found the difference of the square roots of the lengths of the legs.
C.
She took the square root of the difference of the lengths of the legs.
D.
She took the square root of the sum of the lengths of the legs.

Answer 1

D. She took the square root of the sum of the lengths of the legs.

Reason: the hypotenuse is sqrt(a^2 + b^2). The student appears to have used sqrt(a + b) instead of sqrt(a^2 + b^2). For example, with legs 6 and 8 the correct hypotenuse is 10, but sqrt(6+8)=sqrt(14)≈3.74, which is wrong.