Q22 of 118 Page 5

Mark the correct alternative in the following:

If tan θ + sec θ = ex, then cos θ equals


We know tan2x + 1 = sec2x…(1)


Let tan θ be a and sec θ be b


According to question


a + b =ex


Manipulating and Substituting in 1 we get


⇒ a2 – b2 = -1


⇒ (a-b)( a + b) = -1


⇒ (a-b).ex =-1


⇒ a-b = -e-x


a + b =ex


a-b = -e-x


subtracting above equations we get


2b =ex +e-x




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