Question

sin 20° + sin 40°-sin 80º =
1) -1 2) 1
3) 2
4) 0​

Answer 1

Answer:

4) 0

Step-by-step explanation:

             

           sin 20° + sin 40° - sin 80°

= sin 40° + sin 20° - sin 80°m

= 2 sin 60° cos 20° - sin (60° + 20°)

= 2 sin 60° cos 20° - [sin (60°) cos 20° + cos (60°) sin 20°]

= 2 sin 60° cos 20° - sin (60°) cos 20° - cos (60°) sin 20°

= sin 60° cos 20° - sin (60°) cos 20°

= 0