Question

Prove that : cos 30 degree . cos 60 degree - sin 30 degree . sin 60 degree = 0

Answer 1

Answer:

As we know that:

cos 60° = 1/2, cos 30° = √3/2, sin 60° = √3/2, sin 30° = 1/2

Substituting all the values in the given expression,

(1/2 × √3/2) + (√3/2 × 1/2)

= √3/4 + √3/4

= 2√3/4

= √3/2

Thus, (cos 60° × cos 30°) + (sin 60° × sin 30°) = √3/2

Step-by-step explanation:

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Answer 2

Answer:

(√3/2 × 1/2 ) - ( 1/2 × √3/2 )

= √3/4 - √3/4

= 0

Hence, proved that (cos 30° x cos 60° ) - ( sin 30° x sin 60° ) = 0 .

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