1. What is the sine of 45°?
- A
- B
- C
- D1
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Answer: B)
The sine of 45° is , a standard angle value.
Class 10 Introduction to Trigonometry — practice questions with answers
Trigonometry · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.
2. In a right triangle ABC right-angled at B, the side opposite to angle A is called the:
- Ahypotenuse
- Bperpendicular (opposite side)
- Cbase (adjacent side)
- Dmedian
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Answer: B) perpendicular (opposite side)
With respect to angle A, the side BC opposite to it is the perpendicular or opposite side; AB is the base and AC is the hypotenuse.
3. The value of (sin 30° + cos 30°) is:
- A
- B
- C1
- D
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Answer: A)
sin 30° = and cos 30° = , so their sum is .
4. For which standard angle is the tangent ratio undefined?
- A0°
- B30°
- C45°
- D90°
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Answer: D) 90°
tan θ = sin θ / cos θ. At 90°, cos 90° = 0, so the ratio is undefined.
5. Assertion (A): For 0° < θ < 90°, the value of sec θ is always greater than or equal to 1. Reason (R): sec θ = and cos θ lies between 0 and 1 for these angles. Which option is correct?
- ABoth A and R are true and R is the correct explanation of A.
- BBoth A and R are true but R is not the correct explanation of A.
- CA is true but R is false.
- DA is false but R is true.
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Answer: A) Both A and R are true and R is the correct explanation of A.
For 0° ≤ θ < 90°, cos θ is between 0 and 1, so its reciprocal sec θ is at least 1. R correctly explains A.
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