Question

sin(70°) =

A) sin(50°)cos(20°) − cos(50°)sin(20°)

B) sin(50°)cos(20°) + cos(50°)sin(20°)

C) cos(50°)cos(20°) − sin(50°)sin(20°)

D) cos(50°)cos(20°) + sin(50°)sin(20°)

E) cos(20°)sin(20°) − sin(50°)cos(50°)

Answer 1

@dude

Answer 2

sin(α + β) = sin(α) cos(β) + cos(α) sin(β)

Answer 3

Apply the formula. You can let alpha=50 and beta=20. Now you need to plug the values into the formula above.

Answer 4

is it D

Answer 5

if i'm not mistaken

Answer 6

Careful

You're multiplying sin by cosine, not cosine by cosine

Answer 7

eliminate D, B, and E

It's A

Answer 8

The equation they gave you was adding D:
\(sin(α + β) = sin(α) cos(β) \bf{\color{red}{+}}\) \( cos(α) sin(β)\)

Only adding equations are B and D

D is wrong, low and behold

Answer 9

ok it has to be B

Answer 10

Ya