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Prove that: cos 30° . cos 60° - sin 30° . sin 60°  = 0 - Mathematics

Sum

Prove that:

cos 30° . cos 60° - sin 30° . sin 60°  = 0

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Solution

LHS=cos 30°. cos 60° - sin 30°. sin 60°

= `(sqrt3)/(2) (1)/(2) – (1)/(2) (sqrt3)/(2) = (sqrt3)/(4) – (sqrt3)/(4) = 0 = RHS`

Concept: Trigonometric Ratios of Some Special Angles
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APPEARS IN

Selina Concise Mathematics Class 9 ICSE
Chapter 23 Trigonometrical Ratios of Standard Angles [Including Evaluation of an Expression Involving Trigonometric Ratios]
Exercise 23 (A) | Q 3.2 | Page 291
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