The bar graph shows the number of each item sold at a bake sale. Which statement about the graph is true?

A. 25% of the items sold were cookies.
B. 1% more cupcakes than cookies were sold.
C. 1/4 of the items sold were brownies.
D. 1/8 of the items sold were cookies.

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) = .