Question

prove that cos2a/cosa =cosa​

Answer 1

Cos(2a) =cos^2a - sin^2a = 2cos^2a -1 .... So if we devide by cosa ... 2cosa - seca
So it is not cosa
But... If u meant cos^2a .... Then cos^2a = (cosa)(cosa)... If we devide by cos a it comes cosa

Answer 2

$\huge\bf{QUESTION}$

To prove____ LHS = RHS

$\tt\large\green\rightarrow{\frac{Cos ^{2}A}{CosA}=Cos A}$

___________________

$\huge\tt{GIVEN}$

$\tt\large\rightarrow$RHS = Cos A

⠀

$\tt\large\rightarrow$LHS = $\tt\large{\frac{Cos ^{2}A}{CosA}}$

___________________

$\huge\tt{Answer}$

$\tt\large\red\rightarrow$LHS = $\tt\large{\frac{Cos ^{2}A}{CosA}}$

⠀

$\tt\large\red\rightarrow{\frac{Cos A.Cos A}{CosA}}$

$\tt\large\red\rightarrow{\frac{\cancel{Cos A}Cos A}{CosA}=Cos A}$

$\tt\large\red\rightarrow{Cos A}$

___________________

Thus,

$\tt\large\green\rightarrow$ LHS = RHS

___________________