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# Solve cos 30° cos 35° - sin 30° sin 35° # Solve cos 30° cos 35° - sin 30° sin 35°

Question
Trigonometric equation and identitie asked 2020-10-18
Solve \cos 30° \cos 35° - \sin 30° \sin 35°

## Answers (1) 2020-10-19
Use the sum identity for cosine:
$$\cos(A+B)=\cosA\cosB-\sinA\sinB=\cos(30°+35°)$$
$$=cos65°$$

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