Question

Solve 4 sec sqrd x = 8

Answer 1

                                                4 sec²(x)  =  8

Divide each side by  4:                   sec²(x) = 2

Take the square root of each side:    sec(x) = + or - √2

We know that sec(x) = 1/cos(x)

So the equation becomes                1/cos(x) = + or - √2

Divide '1' by each side:                    cos(x)  =  + or -  (1/2) √2

       x =  45°,  135°,  225°,  315°