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sin(90° − θ) = cos θcos(90° − θ) = sin θtan(90° − θ) = cot θcot(90° − θ) = tan θsec(90° − θ) = cosec θcosec(90° − θ) = sec θ
FORMULA CHAPTER
Chapter 24 – Trigonometric Ratios of Complementary Angles
WBBSEClass 10Mathematics1 formulas
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Complementary-Angle Trigonometric Identities
sin(90° − θ) = cos θcos(90° − θ) = sin θtan(90° − θ) = cot θcot(90° − θ) = tan θsec(90° − θ) = cosec θcosec(90° − θ) = sec θ
SymbolMeaningUnit
θangle°
Worked example
Given: θ=30° Calculation: sin(90°−30°)=sin60° Answer: sin60°=cos30°=√3/2.