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A diagonal of a rectangle is 17 cm and one side is 8 cm. Find the length of the other side in cm.

Class 10Triangles (Similarity)Geometry — Similarity
  • A16
  • B15
  • C30
  • D14

Step-by-Step Solution

The diagonal is the hypotenuse: other side = cm.
Answer: B) 15

Key idea: Three similarity criteria

**AA (Angle-Angle)**: Two angles equal → similar. (Third angle is automatic by 180° angle sum.)

**SSS (Side-Side-Side proportionality)**: All three pairs of corresponding sides in same ratio → similar.

**SAS (Side-Angle-Side)**: Two pairs of sides proportional AND included angles equal → similar.

**Important**: SSA does NOT prove similarity (just like for congruence).

AA is by far the most-used in problems: spot two equal angles (often via parallel lines or shared angle) and declare similarity.

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