Question

Sin (30° + Φ) + Cos (60° + Φ) = cos Φ
Φ = Teta ya kak.
Tolong sama cara²nya y kak, Thx.

Answer 1

Verified answer

sin 30 = cos 60 = 1/2

Sin (30° + Φ) + Cos (60° + Φ)
= sin 30 . cos Φ + cos 30 . sin Φ  + (cos 60 . cos Φ   -  sin 60 . sin Φ)
= 1/2 . cos Φ + (1/2 . sin Φ) + 1/2 . cos Φ - (1/2 . sin Φ)
= 1/2 . cos Φ + 1/2 cos Φ
= cos Φ

Answer 2

Verified answer

TriGonoMetRi

sin (30 + θ) + cos (60 + θ)
= sin (90 - (60 - θ)) + cos (60 + θ)
= cos (60 - θ) + cos (60 + θ)
= 2 cos 60 cos θ
= 2 . 1/2 . cos θ
= cos θ
TerBukTi


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2 cos x cos y = cos (x + y) + cos (x - y)
sin (90 - x) = cos x