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if 1+cos^(2)theta=3sinthetacostheta then...

if `1+cos^(2)theta=3sinthetacostheta` then the integral value of `cottheta` is `(0 lt theta lt (pi)/(2))`

A

2

B

1

C

3

D

0

लिखित उत्तर

Verified by Experts

The correct Answer is:
b

Given, `1+cos^(2)theta=3sintheta.cos theta`
`[Oltthetaltpi//2]`
` 1+cos^(2)theta=3sin theta.cos theta`
Dividing by `sin^(2)theta.cos theta`
`rArrco s ec^(2)theta+cot^(2)theta=3cottheta`
`rArr1+cot^(2)theta+cot^(2)theta=3cottheta`
`because [1+cot^(2)theta=co s ec^(2)theta]`
`rArr1+2cot^(2)theta=3cottheta`
`rArr2cot^(2)theta=3cottheta-1`
Let `theta=45^(@)`
`because Cot 45^(@)=1`
`2cot^(2)45^(@)-3cot45^(@)+1=0`
2-3+1=0
0=0
Therefore `cot theta=cot45^(@)=1`
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