IP Maths Notes (Lower Sec, Year 1-2): 06) Geometry, Congruency & Similarity

Q: What does IP Maths Notes (Lower Sec, Year 1-2): 06) Geometry, Congruency & Similarity cover?
A: Apply angle rules, triangle congruency tests, similarity ratios, and prove properties of polygons and circles.

Geometry proofs reveal structure: angles encode relationships, congruency secures shape equality, similarity scales figures. This note consolidates core rules.

Learning targets

• Quote and apply angle properties of parallel lines, polygons, and circles.
• Use triangle congruency tests (SSS, SAS, ASA, RHS) logically.
• Apply similarity ratios to find missing lengths and areas.
• Structure geometry proofs with clear statements and reasons.

1. Angle properties refresher

• Straight line: adjacent angles sum to $180^\circ$.
• Vertically opposite angles are equal.
• Alternate angles and corresponding angles are equal when lines are parallel.
• Interior angles on the same side of a transversal sum to $180^\circ$.

Polygons

Sum of interior angles in an $n$