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प्रश्न
Without using tables, evaluate the following: sin60° sin30°+ cos30° cos60°
उत्तर
sin60° sin30°+ cos30° cos60°.
sin60° = `sqrt(3)/(2)`
sin30° = `(1)/(2)`
cos30° = `sqrt(3)/(2)`
cos60° = `(1)/(2)`
sin60° sin30° + cos30° cos60°
= `sqrt(3)/(2) xx (1)/(2) + sqrt(3)/(2) xx (1)/(2)`
= `sqrt(3)/(4) + sqrt(3)/(4)`
= `(2sqrt(3))/(4)`
= `sqrt(3)/(2)`.
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