Ex 8.4, 3
Last updated at Dec. 8, 2016 by Teachoo
Transcript
Ex 8.4, 3 Evaluate : ( sin2 63° + sin2 27°)/(cos2 17° + cos2 73°) ( sin2 63° + sin2 27°)/(cos2 17° + cos2 73°) = (sin2 (90 − 27) + sin2 27°)/(cos2 (90 − 73) + cos2 73°) = (cos^2 (27°) + sin2 27°)/(sin^2 (73°) + cos^2〖73°〗 ) = 1/1 = 1 Hence, ( sin2 65° + sin2 27°)/(sin2 17° + sin2 73°) = 1 Ex 8.4, 3 Evaluate : sin 25° cos 65° + cos 25° sin 65° sin 25° cos 65° + cos 25° sin 65° = sin (90 – 65) cos 65° + cos (90 – 65) sin 65° = cos 65° × cos 65° + sin 65° × sin 65° = cos265° + sin265° = 1 Hence, sin65° cos 65° + cos 25° sin 65° = 1
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