Solve the following equation: cosec x=1+cotx - Mathematics

Question

Solve the following equation:

`cosec x = 1 + cot x`

Sum

Solution

Given,

`cosec x = 1 + cot x`

⇒ `1/sin x = 1 + cos x/sin x`

⇒ sin x + cos x = 1

In all such problems we try to reduce the equation in an equation involving single trigonometric expression.

∴ `s 1/sqrt2 sin x + 1/sqrt2 cos x = 1/sqrt2` {dividing by √2 both sides}

⇒ `sin x sin pi/4 + cos pi/4 cos x = cos pi/4.` {cos A cos B + sin A sin B = cos(A − B)}

NOTE: The ratio of sin can also be used in place of cos; the answer stays the same, but the form may change. If you enter numbers for n, you will receive the same values in both forms.

If cos x = cos y, impls x = 2nπ ± y, where n ∈ Z

∴ `x - pi/4 = (2npi ± pi/4).`

∴ `x = (2npi ± pi/4) + pi/4` where n n ∈ Z

`x = 2npi or x = 2npi + pi/2` where n n ∈ Z

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Trigonometric Equations

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Q 6.4 Q 6.3 Q 7.1

Chapter 11: Trigonometric equations - Exercise 11.1 [Page 22]

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RD Sharma Mathematics [English] Class 11

Chapter 11 Trigonometric equations
Exercise 11.1 | Q 6.4 | Page 22

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