Class 11 Maths Chapter 3 Trigonometric Functions – Revision Notes

Quick revision notes for Class 11 Maths Chapter 3 (Trigonometric Functions). These Class 11 Maths Chapter 3 notes are ideal for quick revision just before exams.

Angle Measure

• π radians = 180°.
• 1 radian: angle subtended by arc = radius.

Quadrant Signs (All Sin Tan Cos)

• QI: all +; QII: sin+; QIII: tan+; QIV: cos+.

Key Identities

• sin²θ+cos²θ=1; 1+tan²θ=sec²θ; 1+cot²θ=cosec²θ.

Sum/Difference Formulas

• sin(A±B)=sinAcosB±cosAsinB.
• cos(A±B)=cosAcosB∓sinAsinB.

Trigonometric Equations

• Periodic → infinitely many solutions; general solution uses integer parameter n.

One-Line Summary

Trigonometric functions extend beyond acute angles using radians and the unit circle, governed by core identities and sum/difference formulas, with equations yielding infinitely many periodic solutions.

Written by Satish

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