Triangles & the Pythagorean Theorem
In a right triangle, a² + b² = c², where c is the hypotenuse.
The rules
- The hypotenuse is the longest side, opposite the right angle.
- Common triples: 3-4-5, 5-12-13, 8-15-17.
- Special triangles: 45-45-90 has sides 1:1:√2, and 30-60-90 has sides 1:√3:2.
- Area of a triangle = ½ · base · height.
Watch out: Adding the legs or forgetting to take the square root.
Worked example
A right triangle has legs 6 and 8. What is the hypotenuse?
- 36 + 64 = 100.
- √100 = 10.
Answer: 10
Try it yourself
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