Math, asked by mahiraathani, 1 year ago

sin10°sin30°sin50°sin70°=1/16

Answers

Answered by TheLifeRacer
5
Hey !!!

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Answered by sandy1816
2

sin10sin30sin50sin70 \\  \\  =   \frac{1}{2} sin10sin50sin70\\  \\  =   \frac{1}{2}    \times \frac{1}{2} (2sin10sin50)sin70 \\  \\  =  \frac{1}{4} (cos(10 - 50) - cos(10 + 50))sin70 \\  \\  =  \frac{1}{4} (cos40 - cos60)sin70 \\  \\  =  \frac{1}{4} (cos40sin70 -  \frac{1}{2} sin70) \\  \\  =  \frac{1}{8} (2cos40sin70 - sin70) \\  \\  =  \frac{1}{8} (sin(40 + 70) - sin(40 - 70) - sin70) \\  \\  =  \frac{1}{8} (sin110 + sin30 - sin70) \\  \\  =  \frac{1}{8} (sin(90 + 20) + sin30 - sin(90 - 20)) \\  \\  =  \frac{1}{8} (cos20 +  \frac{1}{2}  - cos20) \\    \\  =  \frac{1}{8}  \times  \frac{1}{2}  \\  \\  =  \frac{1}{16}

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