Question

If sec theta -tan theta =4,then find the value of cos theta

Answer 1

this is the right answer

Answer 2

Heya!!

Let theta = x

Sec x - Tan x = ( 1 - Sin x ) / Cos x = 4

=>

4Cos x = 1 - Sin x

put Cos x = z

4z = 1 - √( 1 - z²)

(4z - 1)² = (-√(1-z²))²

16z² + 1 - 8z = 1 - z²

17z² -8z = 0

z = 0 or z = 8/17

So, Cos x = 0 or Cos x = 8/17

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