Question #ca2d2

1 Answer
Jan 6, 2018

#1/a#

Explanation:

By cofunction identities #sin(x) = cos(90^circ-x)#

So we have #sin(40^circ) = cos(90^circ-40^circ)=cos(50^circ) = a#

By reciprocal identities we know that #sec(x)=1/cos(x) #, so

#sec(50^circ) = 1/cos(50^circ) = 1/a#.