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90 Minus

Mathematics · Class 11

sin(90-A)=cos A, cos(90-A)=sin A, tan(90-A)=cot A. Complementary. Use to rewrite.

complement
reduce to A, then sign from the quadrant
sin(90-A)=cos A
sine + in Q2
90 MINUS: sin(90-A)=cos A, cos(90-A)=sin A, tan(90-A)=cot A. Complementary. Use to rewrite.
90 MINUS: sin(90-A)=cos A, cos(90-A)=sin A, tan(90-A)=cot A.
WHAT — 90 MINUS: sin(90-A)=cos A, cos(90-A)=sin A, tan(90-A)=cot A. Complementary. Use to rewrite.
WHY — Why it matters: This rule is a separate learning unit inside allied angles. It can be defined, applied, and checked

Right triangle — 90 Minus — original sketch for this lesson (not copied from a textbook).