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3 3... ०05*10%+ 009%50% + 005%70%. जे) 2 B)1 L2amn 140040 aaa AR AA o |
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Answer» cos 10 cos 50 cos 70= (1/2) [ 2 cos 50 cos 70 ] cos 10= (1/2) [ cos 20 + cos 120 ] cos 10= (1/2) [ cos 20 -- 1 / 2 ] cos 10= (1/2) cos 20 cos 10 -- [ 1 / 4 ] cos 10= (1/4) [ 2 cos 20 cos 10 ] -- [ 1 / 4] cos 10= (1/4) [ cos 30 + cos 10 ] -- (1/4) cos 10= (1/4) cos 30= (1/4) sqrt(3)/2= sqrt(3) / 8 |
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