p = sin 40 q = cos110 find expression for cos140 find expression for tan140

sin(40)=sin(180-40)  or sin(40) = sin(140) = p

 

cos(140) = -√(1-sin(140)²) = -√(1-p²)  Cosine is negative in the 2nd quadrant.

 

tan(140) = sin(140)/cos(140) = -p/√(1-p²)  Tangent is also negative in the 2nd quadrant

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