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Solving Cos X=a

Mathematics · Class 12

Cosine is positive in quadrants I and IV and negative in II and III.

Solving cos x=a
rule
worked example
Solving cos x=a: Cosine is positive in quadrants I and IV and negative in II and III.
CONCEPT AND RULE: Cosine is positive in quadrants I and IV and negative in II and III.
METHOD: For solving cos x=a, identify the given information and required result. Select the matching definit
Cosine is positive in quadrants I and IV and negative in II and III.
Worked pattern: cos x=-12 gives x=2pi/3+2npi or 4pi/3+2npi.

Right triangle — Solving Cos X=a — original sketch for this lesson (not copied from a textbook).