Question

`sin^(2)theta-3sintheta+2=0` willl be true if `sin^(2)theta-3sintheta+2=0` सही होगा यदि?
A. `0 le theta lt 90^(@)`
B. `0 lt theta lt 90^(@)`
C. `theta=0^(@)`
D. `theta=90^(@)`.

Answer 1

Correct Answer - d
`sin^(2)theta-3sintheta+2=0`
`rArrsin^(2)theta-2sintheta-sin theta+2=0`
`rArr sin theta(sin theta-2)-1(sin theta-2)=0`
`rArr(sin thea-1)(sin theta-2)=0`
`[sin thetacancel=2]`
`rArr sin theta=1rArrsin90^(@)`
`rArrtheta=90^(@)`
Alternate
Put value of `theta=90^(@)`
[take help from option]
`sin^(2)theta-3sintheta+2=0`
`sin^(2)90^(@)-3sin90^(@)+2=0`
1-3xx1+2 =0
`[sin90^(@)=1]0=0`
[mathced]
so this is answer.