Question

cota - tana= 2 cot20a​

Answer 1

$$\begin{lgathered}\cot(a ) - \tan(a) \\\end{lgathered}$$

cos÷sin-sin÷cos

=cos*2-sin*2÷sin.cos

=cos2a÷sina.cosa

=2cos2a÷2sina.cosa

=2cos2a÷sin2a=2cot2a

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Answer 2

Answer:

cota-tana = (1/tana)-tana

= (1-tan^2a)/tana = 2(1-tan^2a)/2tana = 2/tan2a = 2cot2a

hence proved