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Formula Sheet

Trigonometry — Formula Sheet

Tamil Nadu Board · Class 9 · Mathematics

4 formulas from Trigonometry (Tamil Nadu Board Class 9 Mathematics) on one page, grouped by topic. Covers Introduction to Trigonometric Ratios, Reciprocal.

45 questions30 flashcards4 formulas & key relations5 concepts

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A labeled diagram of a right-angled triangle showing the perpendicular, base, and hypotenuse relative to an acute angle, and defining the six trigonometric ratios (sine, cosine, tangent, cosecant, sec
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4 Entries · 3 Sections

Formulas and Key Relations

Trigonometric Ratios of Special Angles (0°, 30°, 45°, 60°, 90°)

45° comes from isosceles right triangles (sides in ratio 1:1:√2)

30° and 60° come from equilateral triangles (sides in ratio 1:√3:2)

Trigonometric Ratios of Complementary Angles

sin θ = cos(90° - θ) for any acute angle θ

Key relations

Certain angles have well-defined, easy-to-remember trigonometric values: For 45°: sin 45° = cos 45° = 1/√2, tan 45° = 1.

Full sheet with units and worked examples

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Frequently Asked Questions

What are the important topics in Trigonometry for Tamil Nadu Board Class 9 Mathematics?
Key topics in Trigonometry include Introduction to Trigonometric Ratios, Reciprocal Trigonometric Ratios, Trigonometric Ratios of Special Angles (0°, 30°, 45°, 60°, 90°), Trigonometric Ratios of Complementary Angles. Study these first, then practise questions on each for Class 9 exams.
How many formulas are in Trigonometry?
This sheet lists 4 formulas from Trigonometry, grouped by topic. Learn what each symbol stands for so you can apply the formula, not just recall it.
How should I revise Trigonometry for Class 9 exams?
Learn the core ideas first, then work through the 45 practice questions on Trigonometry. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

More resources for Trigonometry

All Tamil Nadu Board Class 9 Mathematics Formula Sheet

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