What should be done first to evaluate the expression? 9 - 4 ÷ 5 + 3 × 6

Add 5 and 3
Multiply by 3 and 6
Divide 4 by 5
Subtract 4 from 9

The measure of an angle is 117°. what is the measure of a supplementary angle?

Prove (a) cosh2(x) − sinh2(x) = 1 and (b) 1 − tanh 2(x) = sech 2(x). solution (a) cosh2(x) − sinh2(x) = ex + e−x 2 2 − 2 = e2x + 2 + e−2x 4 − = 4 = . (b) we start with the identity proved in part (a): cosh2(x) − sinh2(x) = 1. if we divide both sides by cosh2(x), we get 1 − sinh2(x) cosh2(x) = 1 or 1 − tanh 2(x) = .

Can you me find the missing length. i attached an image.