What is the circumference of circular ground in diameter d m ? Find it​

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) = .

This is about circle theorems. someone asap : (

Estimate the time en route from majors airport (area 1) to winnsboro airport (area 2). the wind is from 340° at 12 knots and the true airspeed is 136 knots. magnetic variation is 5° east.