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Complementary Angles — Practice Quiz

ICSE · Class 9 · Mathematics

Try a 4-question quiz on Complementary Angles for ICSE Class 9 Mathematics: tap an answer to check it and see why. 41 questions in the full chapter test.

41 questions28 flashcards18 formulas & key relations5 concepts

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An illustration showing two acute angles whose sum is 90 degrees, defining them as complementary angles. Examples like 30 and 60 degrees, and a general case with x and (90-x) degrees.
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Quick Quiz: Complementary Angles

0/4

Tap an answer to check it instantly. No sign-up needed for these 4.

1

What is the value of sin 30° + cos 60°?

2

If sin 2A = cos 38°, find the value of A:

3

Evaluate: sin² 60° + cos² 60°

4

Which expression equals cot 25°?

41 Questions·
multiple choicemultiple correcttext answer

Sample Questions

1multiple correct

Which of the following are equal to tan 40°?

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cot 50°, cot(90° - 40°), sin 40°/cos 40°, cos 50°/sin 50°

tan 40° = cot(90° - 40°) = cot 50°. Also, tan 40° = sin 40°/cos 40°. Since 40° and 50° are complementary, cos 50° = sin 40° and sin 50° = cos 40°, so cos 50°/sin 50° = sin 40°/cos 40° = tan 40°.

2multiple choice

Calculate: tan 45° × cot 45°

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1

We know that tan 45° = 1 and cot 45° = 1. Therefore, tan 45° × cot 45° = 1 × 1 = 1. Alternatively, since cot θ = 1/tan θ, we have tan θ × cot θ = 1 for any angle θ (except where undefined).

3multiple correct

Which of the following statements are true?

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sin 30° = cos 60°, tan 45° = cot 45°, sec 70° = cosec 20°

For complementary angles: sin 30° = cos(90° - 30°) = cos 60° ✓. tan 45° = cot 45° = 1 ✓. sec 70° = cosec(90° - 70°) = cosec 20° ✓. However, sin 40° ≠ cos 40° since they're equal only when the angle is 45°.

4multiple choice

Find the value of: cos 0° + cos 30° + cos 60° + cos 90°

Show answer

1 + √3/2 + 1/2 + 0

cos 0° = 1, cos 30° = √3/2, cos 60° = 1/2, cos 90° = 0. Therefore, the sum = 1 + √3/2 + 1/2 + 0 = 3/2 + √3/2 = (3 + √3)/2.

+37 more questions on Complementary Angles (ICSE Class 9 Mathematics)

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Frequently Asked Questions

What are the important topics in Complementary Angles for ICSE Class 9 Mathematics?
Key topics in Complementary Angles include Core idea of complementary angles, Sine and cosine complementary identities, Tangent and cotangent complementary identities, Secant and cosecant complementary identities. Study these first, then practise questions on each for Class 9 exams.
How many practice questions are there for Complementary Angles?
There are 41 questions on Complementary Angles. Try the 4-question sample quiz on this page first; each answer shows an explanation when you tap it.

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

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