If `sec^(2)theta+tan^(2)theta=7` then the value of `theta` when `theta(0 letheta le90^(@))` is (यदि `sec^(2)theta+tan^(2)theta=7` है तो `theta` का मान ज्ञात करे जब `theta(0 letheta le90^(@))` हो )

Options

A. `60^(@)`
B. `30^(@)`
C. `0^(@)`
D. `90^(@)`

Answer

a

Explanation

`sec^(2)theta+tan^(2)theta=7`
`rArr1+tan^(2)theta+tan^(2)theta=7`
`rArr2tan^(2)theta=6 `
`rArr tan^(2)theta=3`
`rArrtantheta=sqrt(3)`
`rArrtheta=60^(@)`
Alternate
take help from option
put `theta=60^(@)`
`sec^(2)60^(@)+tan^(2)60^(@)=7`
`(2)^(2)+(sqrt(3))^(2)= 7`
`(2)^(2)+(sqrt(3))^(2)=7`
7=7(matched)
So, `theta=60^(@)`