Tap on image above I need help please help! You don’t have to answer all just the ones you can do please and thank you

Hello,
If you have noticed they are all right angles, which means you can use Pythagorean theorm.
1. a^2 = 40^2 + 9^2
= a^2 + 1600 + 81
= 1681
a^2 = 1681
sovle for "a"
a = 41
hope this helps.