Question #19476

1 Answer
Feb 14, 2017

See answer below.

Explanation:

secy+tany=1/cosy+siny/cosy=(cosy+cosysiny)/cos^2y=

=(cosy(1+siny))/(1-sin^2y)=(cosy(cancel(1+siny)))/((cancel(1+siny))(1-siny))=cosy/(1-siny)

Let's break this down:

  1. Rewrite secy and tany as 1/cosy and siny/cosy
  2. Add the two fractions
  3. Take a factor of cosy from the numerator
  4. Rewrite cos^2y as 1-sin^2y using cos^2y+sin^2y=1
  5. Rewrite 1-sin^2y using the difference of two squares identity
  6. Cancel the common factors