What is the value of x

Question

What is the value of x to the nearest degree if cos x=0.2615?

Answer 1

cosx= .2615

x = cos^-1(.2615)

= about 75 degrees or -75 degrees

and 75+360n degrees where n= any integer

also -75+360n degrees where n = any integer

use a calculator with trig functions

cosines are positive in quadrants I and IV

cos60 = .5

cos90= 0

60<x<90

.2615 = about .25

.25 is midway between 0 and .5

x=75 is midway between 60 and 90