Question

If 2 cos3x = 1, then find the value of sin (2x+5).​

Answer 1

Answer:

Step-by-step explanation:

2cos3x=1 so cos3x=1/2 => cos3x=cos60 =>3x=60+360k (k belong to R)

=> x=20+120k

sin(2x+5)= sin(2*(20+120k+5)=sin(45+240k)

so sin(2x+5) will equal root 2/ 2