Justin is painting one of his living room walls gold. The area of the square wall is 85 ft2. Which measurement is closest to the side length of this wall in feet? it's not 21 apparently

Given the following statements, which is the best

The parabola opens: y=√x-4 (principal square root) up down right left

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) = .