How do you express sin(π4)sin(2π3) without using products of trigonometric functions?

1 Answer
Jul 3, 2018

cos(5π12)cos(11π12)2

Explanation:

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sin(π4)sin(2π3)

sinxsiny=(12)[cos(xy)cos(x+y])

(12)[cos(π42π3)cos(π4+2π3)]

cos(5π12)cos(11π12)2

cos(5π12)cos(11π12)2