Question is in the pucture

Atriangle includes one angle that 72º. which pair could be the measures of the other two angles of the triangle? a. 9º, 9º b. 26º, 46º c. 53º, 55º d. 72º, 108º

How many solutions does the nonlinear system of equations graphed bellow have?

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) = .