Coaching Centre
Area of rectangles and triangles
Units of area and converting between them, and the area formulas for squares, rectangles and triangles.
Units of area
Area counts squares: mm², cm², m², hectares (ha) and km². Because $1$ m $= 100$ cm, $1$ m² $= 100 \times 100 = 10\,000$ cm².
Rectangles and triangles
The height $h$ must be perpendicular to the base. A triangle is half of a rectangle (or parallelogram) with the same base and height.
A triangle with corners (0, 0), B and T. Moving T sideways does not change the area, because the base and height stay the same.
Find the area of a triangle with base $12$ cm and height $7$ cm.
Find the area of a triangle with base $12$ cm and height $7$ cm.
$\tfrac{1}{2} \times 84$.
How many cm² are in $1$ m²?
$100 \times 100$.
Find the area of a $9$ m by $6$ m rectangle.
$9 \times 6$.
Find the area of a square with side $8$ cm.
$8^2$.
A rectangle has area $56$ m² and length $8$ m. Find its width.
$56 \div 8$.
Convert $25\,000$ m² to hectares.
$\div 10\,000$.
A triangle has area $30$ cm² and base $6$ cm. Find its height.
$\tfrac{1}{2} \times 6 \times h = 30$.
Convert $3$ cm² to mm².
$\times 100$.
New numbers every time. Keep going until you get five in a row.