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X and y are complementary… (Class 10 Maths Basic 2025, Q28b)

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MathsCBSE Class 10 · Basic · Board exam 2025, set 430/1/1 · 3 marks · Short answer

CBSE Class 10 Mathematics Basic 2025: question 28(b)

Set in the CBSE Class 10 board exam of 2025, paper 430/1/1, section C, question 28(b), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q28(b) · 3 marks · Short answerPair of Linear Equations in Two Variables

and are complementary angles such that . Express the given information as a system of linear equations in two variables and hence solve it.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 430/1/1.

Hints

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

Hint 1

What is the sum of two complementary angles?

Hint 2

Rewrite the ratio as an equation, then substitute it into the first equation.

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. Complementary angles add up to : ...(1)

    1 mark

  2. , i.e. ...(2)

    1 mark

  3. Substitute (2) in (1): and .

    1 mark

Answer: x + y = 90°, y = 2x; x = 30°, y = 60°

Where the marks are

  • Writes (1 mark)
  • Writes (1 mark)
  • Gets (½ mark) and (½ mark)

Revise the chapter

Practise this chapterBoard-style questions from Pair of Linear Equations in Two Variables, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 430/1/1 (Basic): 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.