Area of a Triangle Worksheets

These area of a triangle worksheets practice one formula, A = base × height ÷ 2, from first examples to real problems. The printable sheets cover whole numbers, decimals, finding a missing base or height, right triangles, word problems and composite shapes, each with an answer key on the last page. The maker above writes new triangles whenever you need another set. Work through each area of a triangle worksheet from easy to hard.

Quick answer: The area of a triangle is half its base times its height: A = b × h ÷ 2. A triangle with a base of 10 cm and a height of 6 cm has an area of 30 cm². This page has 9 free area of triangles worksheets (PDF) with answer keys for grade 6, plus a maker.

Area of a triangle worksheets: ready-to-print samples

A few of the ready PDFs on this page. The full list is under Ready-to-print worksheets, and the maker above makes new problems on demand.

Area of a triangle formula

A = ½ × base × height, which is the same as A = base × height ÷ 2. The base is any side of the triangle; the height is the straight-up distance from that side to the opposite corner, measured at a right angle. The answer is in square units, such as cm² or in².

Why the formula divides by 2

Draw a rectangle around any triangle so it shares the triangle’s base and height. The triangle fills exactly half of that rectangle, so its area is half of base × height. For a slanted triangle the same is true of the parallelogram it makes with a copy of itself turned around.

How to find the area of a triangle: worked examples

Multiply the base by the height, then halve the result. The answer is in square units:

How to find the area of a triangle in 4 steps

1. Choose a side to be the base and measure it.
2. Find the height: the perpendicular distance from that base to the opposite corner.
3. Multiply the base by the height.
4. Divide by 2 and write square units.

Which side is the height?

• The height is the straight-up distance from the base to the opposite corner. It always meets the base at a right angle.
• Any side can be the base, as long as you use the height that goes with it.
• In a right triangle, the two legs are the base and the height, so no extra line is needed.
• In an obtuse triangle the height can fall outside the triangle. Extend the base with a dotted line to measure it.

Area of a right triangle

In a right triangle the two shorter sides (the legs) meet at a right angle, so one leg is the base and the other is the height. Multiply the legs and halve the result; the longest side, the hypotenuse, is not used. Level 4 of the maker practises exactly this:

If you know the hypotenuse but not both legs, find the missing leg first with the Pythagorean theorem.

Finding a missing base or height

Work the formula backwards: double the area, then divide by the side you know. Level 3 practices this:

Composite shapes with triangles

Split the shape into rectangles and triangles, find each area, then add (or subtract a cut-out piece). For a simple house shape with a 10 ft by 6 ft wall and a roof 10 ft wide and 4 ft tall:

Try ten practice problems

A warm-up across all six levels. Answers are in the right-hand column.

Common mistakes with the area of a triangle

Which area of a triangle worksheet should you start with?

Start with whole numbers, add decimals, then work backwards to missing sides. Levels 1, 3 and 5 have a Set B for a retest.

Common Core standard

These worksheets practice the grade 6 geometry standard for area:

Start with the first area of a triangle worksheet, then move on to the harder sheets once the formula feels easy.

More math practice

• Area and perimeter worksheets for rectangles and squares.
• Pythagorean theorem worksheets, the next step with right triangles.
• Geometry worksheets and the area calculator to check answers.
• 6th grade math worksheets.

Last updated: October 2026