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Evaluate the Following 4(Sin4 60° + Cos4 30°) − 3(Tan2 60° − Tan2 45°) + 5 Cos2 45°

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प्रश्न

Evaluate the Following

4(sin4 60° + cos4 30°) − 3(tan2 60° − tan2 45°) + 5 cos2 45°

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उत्तर

4(sin4 60° + cos4 30°) − 3(tan2 60° − tan2 45°) + 5 cos2 45°  ........(i)

By trigonometric ratios we have

`sin 60^@ = sqrt3/2 - cos 30^@(sqrt3/2)   tan 60^@ = sqrt3   tan 45^@ = 1   cos 45^@ = 1/sqrt2`

By substituting above values in (i), we get

`4([sqrt3/2]^4) + [sqrt3/2]^4) - 3([3]^2 - [1]^2) + `5[1/sqrt2]^2` 

`=> 4[9/16 + 9/16] - 3[3 - 1]+ 5[1/2]`

`=> 4. 18/16 - 6 + 5/2`

`=> 1/4 - 6 + 5/2`

`=> 1/4 - 6  + 5/2`

`= 9/2 + 5/2 - 6`

`= 14/2 - 6 = 7 - 6 = 1`

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अध्याय 10: Trigonometric Ratios - Exercise 10.2 [पृष्ठ ४२]

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आर.डी. शर्मा Mathematics [English] Class 10
अध्याय 10 Trigonometric Ratios
Exercise 10.2 | Q 9 | पृष्ठ ४२

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