The dimensions of a rectangular section of forest land are 5.5 × 105 meters and 4.2 × 104 meters. Complete the following sentences.
2.31 × 103
2.31 × 104
2.31 × 105
23.1 × 109
2.31 × 1010
23.1 × 1010
square meters
square kilometers

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) = .

If the value of cos330°is√3/2 then find cos 165°.

In a timed typing test lara typed 63 words per minute.estimate the number of words she should be able to type in half in hour show your work