Mathematics Geometry Procedural 11–14 yrs

Angles in triangles (age 11+)

三角形中的角（11岁以上）

Description

Derive and apply formulae for the area of triangles, parallelograms, and trapezia, and for the volume of cuboids and other prisms (including cylinders), connecting each formula to its geometric reasoning

Mastery Evidence

✓ Calculate the area of a trapezium using A = ½(a + b) × h and explain why the formula works
✓ Find the volume of a triangular prism by calculating cross-sectional area × length
✓ Derive the formula for the volume of a cylinder as π × r² × h by reasoning from the prism formula

Assessment Prompt

If your child needs to tile a triangular section of a patio with a base of 4 m and height of 3 m, can they work out the area to know how many tiles to buy?