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Evaluate the Following Cot 2 30 ∘ − 2 Cos 2 60 ∘ − 3 4 Sec 2 45 ∘ − 4 Sec 2 30 ∘ - Mathematics

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Question

Evaluate the Following

`cot^2 30^@ - 2 cos^2 60^circ- 3/4 sec^2 45^@ - 4 sec^2 30^@`

Sum

Solution

`cot^2 30^circ - 2 cos^2 60^circ - 3/4 sec^2 45^@ - 4 sec^2 30^circ`

By trigonometric ratios we have

`cot 30^@ = sqrt3   cos 60^@ = 1/2  sec 45^@ = sqrt2   sec 30^@ = 2/sqrt3`

By trigonometric ratios we have

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

`3 - 2 xx 1/4 - 3/4 xx 2 - 4 xx 4/3`

= `3/1 - 1/2 - 3/2 - 16/3`

= `(18 - 3 - 9 - 32)/6`

= `(18 - 44)/6`

= `(-26)/6`

= `(-13)/3`

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Chapter 10: Trigonometric Ratios - Exercise 10.2 [Page 42]

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RD Sharma Mathematics [English] Class 10
Chapter 10 Trigonometric Ratios
Exercise 10.2 | Q 12 | Page 42
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