A swimmer breaks a world record by 0.07 seconds. The old record was 49.51 seconds. What is the swimmer's new world record? a. 49.58 seconds
b.49.44 seconds
c.48.81 seconds
d.48.58 seconds

Does the point (1, sqrt 7) lie on circle shown.

Solve the equation by completing the square. x^2+2x=17

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) = .