NCERT Solutions Class 10 Maths Chapter 6 — Triangles#

Chapter 6 covers the concept of similar triangles and the conditions under which two triangles are similar. Key topics include the Basic Proportionality Theorem (Thales’ theorem), its converse, and the AA, SSS, and SAS criteria for similarity of triangles.

exercise 6.1 exercise 6.2 exercise 6.3

Exercises#

  • Exercise 6.1 — Similar figures and basic concepts of similar triangles (3 questions)
  • Exercise 6.2 — Basic Proportionality Theorem and its converse (10 questions)
  • Exercise 6.3 — Criteria for similarity of triangles (AA, SSS, SAS) (16 questions)

What you will learn#

  • What makes two figures similar, and how similarity differs from congruence.
  • The Basic Proportionality Theorem (Thales’ theorem) and its converse.
  • The AAA (or AA), SSS and SAS criteria for similar triangles.
  • Using similar triangles to find unknown lengths and to prove results.

Key formulas and results#

  • Basic Proportionality Theorem: if $DE \parallel BC$ in $\triangle ABC$, then $\dfrac{AD}{DB} = \dfrac{AE}{EC}$.
  • In similar triangles, corresponding angles are equal and corresponding sides are in the same ratio.

Read and revise#

Frequently asked questions#

How many exercises are in Class 10 Maths Chapter 6?
Three: Exercise 6.1 (3 questions), Exercise 6.2 (10 questions) and Exercise 6.3 (16 questions) — 29 questions in all, each solved step by step here.
What is the difference between congruent and similar triangles?
Congruent triangles have the same shape and the same size. Similar triangles have the same shape, but one can be an enlarged or reduced copy of the other.

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