Question #d87ec

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Answer 1 · 2018-01-03T13:04:36

The answer is #=cosasqrt((1+sina)(1-sina))#

#"Reminder"#

#cos^2x+sin^2x=1#

Therefore,

#cos^2a=cosasqrt(1-sin^2a)=cosasqrt((1+sina)(1-sina))#

Also,

#cos^2a=1-sin^2a=(1+sina)(1-sina)#

Answer 2 · 2018-01-03T13:12:09

(see answer below [or maybe above, they seem to move around])
...or, as an alternative:
#color(white)("XXX")cos^2(a)=cos(a)xxcos(a)#

...or, #cos^2(a)=1-(sin(a)xxsin(a))#

I assumed that it was not necessary to use both #cos(a)# and #sin(a)# in the definition.