Mathematics Class 10
Circles
Prove a tangent meets the radius at 90°, and that two tangents from a point are equal.
11 lessons · ~83 min total
Track progress — 0 of 11 lessons read 0%
Lessons in this topic
- 0 Start here A roadmap: the touching line, the count of tangents from a point, and the two theorems this track proves. · 4 min You are here
- 1 Touching, not crossing A tangent touches a circle at exactly one point and never crosses it. · 8 min
- 2 None, one, or two The number of tangents through a point is decided by one comparison with the radius. · 8 min
- 3 The square corner at the contact point The tangent stands at a right angle to the radius through the point of contact — proved. · 9 min
- 4 How long is the touch Join an outside point to the centre and the tangent becomes a leg of a right triangle. · 8 min
- 5 Two tangents, one length Two tangents from one outside point are equal — proved with Pythagoras, then RHS. · 9 min
- 6 Tagging the pieces of a quadrilateral Using the equal-tangents theorem four times: a circle touching all four sides tags equal pieces at each corner. · 8 min
- 7 The angle at the junction Tangent meets radius at 90°, so the other two kite angles add to 180°. · 8 min
- 8 The whole toolkit, on one page Using the tangent right angle and Pythagoras together: a chord of one circle that just touches a smaller one. · 8 min
- 9 The big picture One touching line, two proved theorems, and the right triangle that measures its length. · 5 min
- 10 Track quiz Cheat-sheet table plus a reveal quiz, one question per idea. · 8 min
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