The answer to question 7 is option B. 1/2 yd, 1/2 yd, 3/4 yd. This is because there is no way to rearrange the numbers in the formula a² + b² = c² to get it to be correct, so it cannot be a right triangle.
The answer to question 8 is option H. 3cm. This is because you need to use the formula a² + b² = c², and so do 2² + 5 = 4 + 5 = 9, and then the square root of 9 is 3.
I hope this helps!