How do you solve the following equation cosx(2sinx+1)=0cosx(2sinx+1)=0 in the interval [0, 2pi]?

1 Answer
Oct 2, 2016

"The Soln. Set "={pi/2, 7pi/6, 3pi/2, 11pi/6} sub [0,2pi]The Soln. Set ={π2,7π6,3π2,11π6}[0,2π].

Explanation:

cosx(2sinx+1)=0cosx(2sinx+1)=0

rArr cosx=0, sinx=-1/2cosx=0,sinx=12

cosx=0, and, 0 le x le 2pi rArr x=pi/2, 3pi/2.cosx=0,and,0x2πx=π2,3π2.

sinx=-1/2, &, x in [0,2pi] rArr x=pi+pi/6, or, x=2pi-pi/6,sinx=12,&,x[0,2π]x=π+π6,or,x=2ππ6,

"i.e., "x=7pi/6, 11pi/6.i.e., x=7π6,11π6.

Thus, the Soln. Set ={pi/2, 7pi/6, 3pi/2, 11pi/6} sub [0,2pi]={π2,7π6,3π2,11π6}[0,2π].