Q1
sin²θ+cos²θ equals:
A1
B0
C2
Dθ
CBSEClass 10 (CBSE)MathematicsCh 8 · Topic 2
Trigonometric Identities
Learning key identities relating trigonometric ratios.
Core concept
These identities are used to simplify complex trigonometric expressions, prove other trigonometric statements, and solve trigonometric equations without needing to know the specific angle's value. For example, given sin θ = 3/5, the identity sin²θ+cos²θ=1 can be rearranged to find cos θ = √(1-sin²θ) = √(1-9/25) = √(16/25) = 4/5, demonstrating how one ratio can be found from another using identities.
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CBSE class 10 trigonometric identities
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• Fundamental identity: sin²θ + cos²θ = 1 (from the Pythagoras theorem).
• Other identities: 1+tan²θ=sec²θ and 1+cot²θ=cosec²θ.
• Identities help simplify expressions and find one ratio from another.
• Example: given sin θ=3/5, identity gives cos θ=4/5.