30 points and brainilest to answer this question answer choices are : $168 , 9 , 158 , 10 , 30 , 157 , $100 , 32, $4 , 85 , $167 , 84 , $99 , $46 , $45 , $3

What is the value of x? enter your answer in the box. (cm)

Mary used 1/7 of a spool of ribbon to complete 4 projects. she used the same amount of ribbon on each project. how much ribbon did she use on each project?

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) = .