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Mathematics — CBSE Class 10 board question

Q1. [1]
$\triangle ABC$ and $\triangle PQR$ are shown in the adjoining figures. The measure of $\angle C$ is :
  1. (a) $140°$
  2. (b) $80°$
  3. (c) $60°$
  4. (d) $40°$
Previously asked in CBSE board exam
2025 30/4/1 Q7
Generated by claude-sonnet-4-6 · 2026-06-15 10:26 · grounding rag
Model Answer

(d) 40°

By SSS similarity, △ABC ~ △RQP (since AB/RQ = BC/QP = CA/PR = 1/2). So ∠C = ∠P. In △PQR, ∠P = 180° − 80° − 60° = 40°, therefore ∠C = 40°.

Explanation

This is directly from Example 5 of the textbook (Chapter 6, Section 6.4). The key step is identifying the correct correspondence: A↔R, B↔Q, C↔P. Once △ABC ~ △RQP is established by SSS, ∠C corresponds to ∠P, and ∠P is found by the angle sum property. Examiners expect you to state the similarity criterion and the correct symbolic form of similarity.

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