CBSE Class 10 Mathematics Standard 2025: question 5
Set in the CBSE Class 10 board exam of 2025, paper 30/1/1, section A, question 5, for 1 mark. Try it first; the hints and our step-by-step solution are below.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 30/1/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
What is equal to?
Hint 2
Use the identity .
Step-by-step solution
Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.
Since , the bracket equals .
- 1 mark
So the expression is , using . This is option (C).
Answer: −1, option (C)
Where the marks are
- Writes the bracket as and uses to get , option (C) (1 mark)
Revise the chapter
- Chapter: Introduction to Trigonometry (notes, formulas, where marks are lost and every past question)
- Topic: Proving Simple Trigonometric Identities
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The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.