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Question
`"cos" 2 theta` is not equal to ____________.
Options
`2 "cos"^2 theta - 1`
`1 - 2 "sin"^2 theta`
`(1 + "tan"^2 theta)/(1 - "tan"^2 theta`
`(1 - "tan"^2 theta)/(1 + "tan"^2 theta`
MCQ
Fill in the Blanks
Solution
`"cos" 2 theta` is not equal to
`underline((1 + "tan"^2 theta)/(1 - "tan"^2 theta))`.
Explanation:
`"cos" 2 theta` is not equal to
`"cos" (theta + theta) = "cos" theta . "cos" theta - "sin" theta . "sin" theta = "cos"^2 theta - "sin" ^2 theta`
`= ("cos"^2 theta - "sin"^2 theta)/("cos"^2 theta + "sin"^2 theta)`
`= (1 - "tan"^2 theta)/(1 + "tan"^2 theta)`
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