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If (A – B) = 1/2, (A + B) =… (Class 10 Maths 2024, Q23b)

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MathsCBSE Class 10 · Standard · Board exam 2024, set 30/4/1 · 2 marks · Very short answer

CBSE Class 10 Mathematics Standard 2024: question 23(b)

Set in the CBSE Class 10 board exam of 2024, paper 30/4/1, section B, question 23(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q23(b) · 2 marks · Very short answerIntroduction to Trigonometry

If , ; , ; find and .

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 30/4/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Which standard angle has sine equal to ½, and which has cosine equal to ½?

Hint 2

You get two linear equations in A and B; add them.

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.

  1. ...(i)

    ½ mark

  2. ...(ii)

    ½ mark

  3. Adding (i) and (ii): ; then .

    1 mark

Answer: ∠A = 45°, ∠B = 15°

Where the marks are

  • A − B = 30° (½ mark)
  • A + B = 60° (½ mark)
  • Solving to get A = 45°, B = 15° (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Introduction to Trigonometry, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 30/4/1 (Standard): every question, by section.

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.