Question

solve the equation in the specified interval.
1. sec x=-3, -π≤x<π
2. sin x=-0.5, -∞ 12 years ago

Answer 1

secx=-3
1/cosx = -3
-1/3 = cosx
now -1/3 is about cos(109.47)
so:
cosx = cos(109.47)
so
x1 = 109.47 + 360k

and
x2 = -109.47 + 360k

x1: we can take only k=0 so
109.47
and x2 we can take only k=0 so
-109.47

two solutions : 109.47,-109.47