Trigonometry Angle Sum and Difference, Double Angle and Half Angle Formulas Find the exact value of: Sin 85* cos 20* - Cos 85* sin 20*

Question

asked Jun 21, 2021 150k views

1 Answer

Romac · Answer 1 · 2021-06-27T01:22:22+0000

Answer:

sin(105)

Explanation:

Apply the trig identity: sinAcosB+cosAsinB = sin(A+B)

integrating that into the question to find A and B

sin(85)cos(20)+cos(85)sin(20)

= sin(85+20) = sin(105)