2026 · Basic · Set 1 · Part 2·Q32·5 marks

Triangles

Question

State "Basic Proportionality Theorem" and use it to prove the following: A line through the mid-point of one side of a triangle, parallel to another side, bisects the third side.

Approach

State BPT: a line parallel to one side divides the other two sides proportionally. Apply this with the midpoint condition to show the line bisects the third side.

Step-by-step working

  1. 1

    State BPT: If a line is parallel to a side of triangle, it divides the other two sides proportionally

    1 mark
  2. 2

    Let D be midpoint of AB, and DE BC

    1 mark
  3. 3

    By BPT:

    1.5 marks
  4. 4

    Since AD = DB, we get AE = EC, so E bisects AC

    1.5 marks

Concepts used

basic proportionality theoremmidpoint theoremparallel lines

Similar question types

Stuck on a similar question? Ask the Aethez tutor — it walks you through any Class 10 Maths question step by step.