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Pythagoras' theorem only works in a right-angled triangle. Find the 90∘90^\circ90∘ angle first. The side opposite the right angle is the hypotenuse, which is always the longest side.
If the two shorter sides are aaa and bbb, and the hypotenuse is ccc, then
a2+b2=c2 a^2 + b^2 = c^2 a2+b2=c2This means the squares of the two shorter sides add to the square of the longest side.
Before you calculate, label the right angle and the hypotenuse. Also make sure every side length is in the same unit before you substitute into the formula.
Question 1
3 marksA right-angled triangle ABC ABC\,ABC is shown. The right angle is at vertex BBB. The horizontal side AB AB\,AB is 4.8 cm. The vertical side BC BC\,BC is 3.6 cm.
Calculate the length of ACACAC.
What specific type of triangle is required to use Pythagoras' theorem?
Revision notes for Edexcel GCSE Maths Pythagoras. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.
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Triangle ABCABCABC has a right angle at AAA. Which side is the hypotenuse?
