Answer:
x = pi/2 and 11pi/6
Step-by-step explanation:
Given the trigonometry expression
cosx (2 sinx+1)=0
This can be written in two forms as;
cosx = 0 and 2sinx + 1 = 0
If cos x = 0
x = arccos0
x = 90degrees
x = pi/2
Similarly
2sinx + 1 = 0
2sinx = -1
sinx = -1/2
sinx =-0.5
x = aarcsin(-0.5)
x = -30
Since sin is negative in the third and 4th quadrant
x = 270 + 30
x = 330degrees
x = 330pi/180
x = 11pi/6
