Introduction to Trigonometry Notes

✓ Free notes Class 10 Math 1 study file

About these notes

Class 10 Math Introduction to Trigonometry CBSE gives clear notes, important questions and MCQ practice to learn trig ratios, reciprocals and core identities. Main sub-topics: trig ratios from right triangles (definitions), exact values for 30°, 45°, 60°, reciprocals (sec, cosec, cot), Pythagorean identity sin^2θ + cos^2θ = 1 and 1 + tan^2θ = sec^2θ, complementary relations and simplification techniques (convert sec/cosec to 1/cos or 1/sin). Ideal for Class 10 students of CBSE and Bihar Board preparing for chapter test, class tests, board revision and quick question answer drills.

Key points you will learn

Class 10 Math Introduction to Trigonometry notes — sin = opposite/hypotenuse, cos = adjacent/hypotenuse, tan = opposite/adjacent
Reciprocals: sec = 1/cos, cosec = 1/sin, cot = 1/tan and when to convert them
Exact values: sin30°=1/2, sin45°=√2/2, sin60°=√3/2 and corresponding cos values
Pythagorean identity: sin^2θ + cos^2θ = 1; derive 1 + tan^2θ = sec^2θ
Complementary-angle rules: sin(90°−θ)=cosθ, tan(90°−θ)=cotθ
Simplification tip: substitute exact surd forms first, simplify algebraically, then convert to decimal
Practice focus: verify identities step-by-step, quick substitution and algebraic simplification for MCQ and chapter test problems

What is inside this chapter

📄

Introduction to Trigonometry

📥 Open notes

Questions students ask

What is sin 45°?

sin 45° = √2/2. In a right triangle with equal legs the ratio opposite/hypotenuse equals 1/√2 which is √2/2; use the exact surd in identity proofs and convert to 0.7071 only when a decimal is required.

What is sin 30°?

sin 30° = 1/2. From an equilateral triangle halved, the opposite side is half the hypotenuse; use 1/2 directly in exact calculations and change to 0.5 only for decimals.

What is cos 60°?

cos 60° = 1/2. Cosine of 60° equals sine of 30° by complementary relation; keep the fractional form 1/2 for algebraic simplification and use decimals only if asked.

Evaluate: (cos45° + sin60°) / (sec30° + cosec30°).

Exact value = (√6 + 3) / [4(1 + √3)]. Substitute cos30°=√3/2 and sin30°=1/2, simplify algebraically to this fraction and convert to ≈0.499 only at the end.

Where to find Class 10 Math Introduction to Trigonometry notes and important questions?

On Merit Spring ROH look for the note titled 'Introduction to Trigonometry' for chapter notes; use the site-wide chapter tests and mock tests for MCQ practice and question answer drills to revise for class or board tests.

More Math chapters

Real Numbers Polynomials Pair of Linear Equations in Two Variables Quadratic Equations Arithmetic Progressions Triangles All chapters →

Class 10 — other subjects

Science Social Science Computer ENGLISH HINDI SANSKRIT

Merit Spring App install karein

App Theme