Question

find cos 90+x if cosx = 4/5 if x lie between 0to 90
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Answer 1

cos(90 + x) = - sinx

cos x= 4/5

sin x= √1-16/25 = √9/25 = 3/5

cos(90+ x) = - 3/5,

or

cos x= 4/5,

as we know cos 37 = 4/5

x= 37

cos( 90 + 37) = - sin 37

and sin 37 = 3/5

= -3/5

or cos90 cos37 - sin90 sin37

cos90= 0

So -sin90 sin37

-sin37= -3/5

Answer 2

ur answer .....tell me if its correct..