Question

cos a/(1+sin a)+(1+sin a)/cos a化简

Answer 1

cos a/(1+sin a)+(1+sin a)/cos a

= cos a*(1-sina)/[(1+sin a)(1-sina)]+(1+sin a)cosa/cos² a

= cosa(1-sina)/(1-sin²a)+(1+sin a)cosa/cos² a

=cosa(1-sina)/cos²a+(1+sin a)cosa/cos² a

=[cosa(1-sina)+(1+sina)cosa]/cos²a

=2cosa/cos²a

=2/cosa