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Chapter 22 of 28
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Trigonometrical Ratios

ICSE · Class 9 · Mathematics

Flashcards for Trigonometrical Ratios — ICSE Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.

36 questions26 flashcards5 concepts

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A right-angled triangle with one acute angle labeled as the angle of reference. The sides opposite to the acute angle, adjacent to the acute angle, and opposite to the right angle are clearly labeled
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26 Flashcards
Card 1Pythagoras theorem in trigonometry

In a right-angled triangle ABC, the hypotenuse AC = 13 cm and one leg AB = 5 cm. Find BC.

Answer

Step 1: Use Pythagoras theorem: AC^2 = AB^2 + BC^2. Step 2: Put the values: 13^2 = 5^2 + BC^2. Step 3: 169 = 25 + BC^2. Step 4: BC^2 = 144. Step 5: BC = 12 cm. Answer: BC = 12 cm.

Card 2Sine ratio

For angle A in triangle ABC, what is sin A when BC = 12 cm and AC = 13 cm?

Answer

Step 1: For angle A, sin A = perpendicular / hypotenuse. Step 2: Here, perpendicular = BC and hypotenuse = AC. Step 3: sin A = BC / AC = 12 / 13. Answer: sin A = 12/13.

Card 3Cosine ratio

For angle A in triangle ABC, find cos A when AB = 5 cm and AC = 13 cm.

Answer

Step 1: For angle A, cos A = base / hypotenuse. Step 2: Here, base = AB and hypotenuse = AC. Step 3: cos A = AB / AC = 5 / 13. Answer: cos A = 5/13.

Card 4Tangent ratio

For angle A in triangle ABC, find tan A when BC = 12 cm and AB = 5 cm.

Answer

Step 1: For angle A, tan A = perpendicular / base. Step 2: Here, perpendicular = BC and base = AB. Step 3: tan A = BC / AB = 12 / 5. Answer: tan A = 12/5.

Card 5Cosecant ratio

For angle A in triangle ABC, find cosec A when AC = 13 cm and BC = 12 cm.

Answer

Step 1: For angle A, cosec A = hypotenuse / perpendicular. Step 2: Here, hypotenuse = AC and perpendicular = BC. Step 3: cosec A = AC / BC = 13 / 12. Answer: cosec A = 13/12.

Card 6Secant ratio

For angle A in triangle ABC, find sec A when AC = 13 cm and AB = 5 cm.

Answer

Step 1: For angle A, sec A = hypotenuse / base. Step 2: Here, hypotenuse = AC and base = AB. Step 3: sec A = AC / AB = 13 / 5. Answer: sec A = 13/5.

Card 7Finding all ratios from one ratio

If cot A = 4/3 in a right-angled triangle, find all other trigonometrical ratios of angle A.

Answer

Step 1: cot A = base / perpendicular = 4 / 3. Step 2: Let base = 4x and perpendicular = 3x. Step 3: Hypotenuse^2 = (4x)^2 + (3x)^2 = 16x^2 + 9x^2 = 25x^2. Step 4: Hypotenuse = 5x. Step 5: sin A = 3x /

Card 8Expression using sec and tan

If 13 sin A = 12, find sec A - tan A.

Answer

Step 1: 13 sin A = 12, so sin A = 12/13. Step 2: Let perpendicular = 12x and hypotenuse = 13x. Step 3: Use Pythagoras theorem: AB^2 + (12x)^2 = (13x)^2. Step 4: AB^2 = 169x^2 - 144x^2 = 25x^2. Step 5:

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Frequently Asked Questions

What are the important topics in Trigonometrical Ratios for ICSE Class 9 Mathematics?
Trigonometrical Ratios covers several key topics that are frequently asked in ICSE Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Trigonometrical Ratios — ICSE Class 9 Mathematics?
Understand the core concepts first, then work through the 36 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Trigonometrical Ratios?
There are 26 flashcards for Trigonometrical Ratios covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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