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Show that cos40cos80cos160=-1/8 |
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Answer» Mujhe samajh ni aaya We havecos40°cos80°cos160°=>{(2sin40°cos40°)cos80°cos160°}/2sin40°=>{(2sin80°cos80°)cos160°}/4sin40°=>{2sin160°cos160°}/8sin40°=>sin320°/8sin40°=>sin(360°-- 40°)/8sin40°=> -- sin40°/8sin40°=> --1/8 |
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