Question

If cos 20° + sin 100° + sin 140° = cos 20° 1+then 2 =
[21h]​

Answer 1

Step-by-step explanation:

u can use cos (a +b) and cos (a-b)

step :- cos(120 -20)

remember cos(90-A) = sin A

similarly sin (90-A) = cos A

u will get benefits after using this.