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Trigonometric Ratios of Particular Angles
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Trigonometric Ratios of Particular Angles
Here we are using the values of standard trigonometric ratios of 0, 30, 45, 60 and 90 for evaluating expressions involving trigonometric ratios. It should be noted that sin2, cos2, tan2 etc. are the squares of the values of sin, cos, tan etc. for given values of .
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Example: Evaluate the following:
cos2 30 cos2 45 + 4 sec2 60 + 1/2 cos2 90 - 2 tan2 60
Solution: We have,
cos2 30 cos2 45 + 4 sec2 60 + 1/2 cos2 90 - 2 tan2 60
= (cos 30)2 (cos 45)2+ 4 (sec 60)2 + 1/2 (cos 90)2 - 2 (tan 60)2
= (3/2)2(1/2)2 + 4(2)2 + 1/2(0)2 - 2(3)2
= (3/8) + 16 + 0 - 6 = 83/8
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