Composite area with triangles: method
When a figure is made from several parts, break it into familiar shapes and find each area separately. For this type of problem, one of the parts is a triangle. Use the triangle area rule:
[A = \frac{1}{2}bh]
where (b) is the base and (h) is the perpendicular height.
Step-by-step method
- Identify each piece of the composite figure.
- Find the area of the triangle using the correct base and height. Make sure the height is perpendicular to the base.
- Find the area of any other shapes if they are part of the figure.
- Add or subtract areas depending on how the figure is built.
- Simplify the final answer fully.
Useful checks
- The height of a triangle must form a right angle with the base.
- If the triangle is not a right triangle, still use the perpendicular height, not a slanted side.
- Your final answer should be in square units.
Quick check
After computing, estimate whether the result is reasonable by comparing it with the size of the whole figure. If the triangle seems small, its area should also be relatively small. Recheck arithmetic if the total looks too large or too small.