Question

prove that 1-sinA/1+sinA=(secA-tanA)²

Answer 1

1-sinA)/(1+sinA) 
=(1-sinA)(1-sinA)/(1+sinA)(1-sinA) 
=(1-sinA)^2/(1-sin^2A) 
=(1-sinA)^2/cos^2A 
={(1-sinA)/cosA}^2 
={(1/cosA)-(sinA/cosA)}^2 
={secA-tanA}^2

Answer 2

here is your answer.