The dot plot shows the birth year of everyone who works at Sam’s office. The youngest person who works there was born in 1987. Sam described the data as having a spread from 1965 to 1987, four gaps, a peak at 1984, and a center of 1978. Where did Sam make an error?

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

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) = .

Anyone? 15m is what percent of 60m; 3m; 30m; 1.5 km?