Class 7 Maths · Ganita Prakash Part 1 · Chapter 7
A Tale of Three Intersecting Lines
Triangles from scratch — the angle sum, the triangle inequality, and what it takes for three lines to make a triangle.
Video coming soon — meanwhile, watch free classes on our YouTube channel →
Rashmi Ma’am teaches the full chapter free on YouTube — watch first, then practise below.
What your child learns
- See why the three angles of every triangle add to 180° — not just memorise it
- Use the angle-sum and exterior-angle relationships to find unknown angles
- Apply the triangle inequality: which side lengths can actually form a triangle
- Classify triangles by sides and angles, and spot special cases
- Solve mixed problems combining triangle rules with the previous chapter’s angle rules
Parent pointer
Ask your child the chapter’s central question at dinner: “Can sticks of 2 cm, 3 cm and 7 cm make a triangle?” If they say no and can say why (2 + 3 < 7), the chapter has done its job. If they start drawing to check — even better, that's real maths.
Stuck on this chapter? Message us — tell us the exercise number and we’ll point you to the right video.
💬 Ask about this chapterPractise it — the Azone loop
Watch the class
Full chapter above, free. Pause and solve along — that’s the rule.
Quick questions parents ask
Is this the old “Triangle and its Properties” chapter?
It covers that territory — angle sum, exterior angle, triangle inequality — but builds it as a story about when three lines can close into a triangle. Same exam-relevant results, better motivation.
How much of this appears in Class 10 boards?
Triangles are the single most-tested geometry topic through Class 10. The angle rules learned here get used every single year from now on — this is a chapter to master, not just pass.
Want this chapter to actually stick?
Join the small live online batch (max 20 students) — weekly tests, doubt solving and a parent report card. Or start with a free demo class.