sin θ cos θ
sin
Chapter 3  ·  Class XI Mathematics

The Circle of All Angles

Trigonometric Functions

Conquer the Unit Circle — The Highest-Weightage Chapter of Class XI

📖 Read Full Notes ⚡ Formula Capsules

Chapter Snapshot

15Concepts
35Formulae
10–12%Exam Weight
5–6Avg Q's
HighDifficulty

Why This Chapter Matters for Entrance Exams

JEE MainJEE AdvancedCBSEBITSATKVPY

Trigonometry is the single most-tested chapter in JEE Main from Class XI — expect 4–6 questions. BITSAT has a dedicated Trigonometry section. Every calculus problem in Class XII relies on trig identities. KVPY conceptual questions frequently involve the unit circle and periodicity.

Key Concept Highlights

Radian Measure
Unit Circle
Trigonometric Ratios
Domain & Range of Trig Functions
Graphs & Periodicity
Compound Angle Formulae
Multiple Angle Formulae
Sum-to-Product
Product-to-Sum
Inverse Trig (intro)
Trigonometric Equations
Signs in Quadrants
Allied Angles
Pythagorean Identities
Half-Angle Formulae

Important Formula Capsules

Trigonometry has 35+ identities — the grid layout helps you see them all at a glance.

$sin²θ + cos²θ = 1$
$sin(A±B) = sinA cosB ± cosA sinB$
$cos(A±B) = cosA cosB ∓ sinA sinB$
$tan(A+B) = (tanA + tanB)/(1 − tanA·tanB)$
$sin 2A = 2 sinA cosA$
$cos 2A = cos²A − sin²A = 1 − 2sin²A = 2cos²A − 1$
$sin C + sin D = 2 sin((C+D)/2) cos((C−D)/2)$

What You Will Learn

Navigate to Chapter Resources

📖 Full Notes Complete NCERT Coverage 🧠 MCQ Practice Topic-wise Questions 🎯 PYQ Bank JEE · CBSE · BITSAT 📘✔️ Exercises Step by step Solutions to textbook exercises ✔️❌ True / False Concept-based True & False questions

🏆 Exam Strategy & Preparation Tips

Create a formula sheet and revise it every morning for 2 weeks — pure memorization yields 5+ marks in JEE. Focus on Compound, Double and Half-angle formulae. Practice solving trig equations with general solutions. NEVER skip this chapter for any exam.


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