Solve each equation on the interval 0≤x<2π .

Question

a) cosx=−1/2

b) 3sinx+5=−2sinx

Answer 1

a) cosines are negative only in quadrants II and III

reference angle is 60 degrees, x = 180+ or - 60 = 120 and 240 degrees

x = 2pi/3 or 4pi/3

b) 3sinx +5 =-2sinx

5sinx =-5

sinx =-1

x= 270 degrees = 3pi/2