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Question Number 151248 by mathdanisur last updated on 19/Aug/21
Answered by EDWIN88 last updated on 19/Aug/21
4sin(4x−60°)sin(6x−60°)sin(480°−10x)+32=0{2sin(4x−60°)sin(6x−60°)}2sin(120°−10x)+sin60°=0{cos2x−cos(10x−120°)}2sin(120°−10x)+sin60°=02cos2xsin(120°−10x)−sin(240°−20x)+sin60°=0sin(120°−8x)−sin(12x−120°)+sin(60°−20x)+sin60°=0sin(120°−8x)+sin60°+sin(60°−20x)−sin(12x−120°)=02sin(90°−4x)cos(30°−4x)+2cos(30°−4x)sin(90°−16x)=02cos4xcos(30°−4x)+2cos(30°−4x)cos16x=02cos(30°−4x){cos16x+cos4x}=04cos(30°−4x)cos10xcos6x=0{cos(30°−4x)=0cos10x=0cos6x=0{cos(4x−30°)=cos90°⇒4x=30°±90°+2kπcos10x=cos90°⇒x=±9°+k.36°cos6x=cos90°⇒x=±15°+k.60°
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