Grade 12th passAlgebra
the value of cos 20+8 sin70*sin 50*sin 10/sin^2(80) is equal to
1 Answer
Arun
Dear student
Sin10sin50sin70 = 2sin10cos10sin50sin70/2cos10
= sin20sin50sin70/2cos10 = 2sin20cos20cos40/4cos10
= 2sin40cos40/8cos10 = sin80/8sin80 = 1/8
cos20 + 8sin10sin50sin70 = cos20 + 1 = 2cos²10 = 2sin²80
(cos20 + 8sin70sin50sin10)/sin²80 = 2.
Regards
Arun (askIITians forum expert)
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