Calculating the length of the hypotenuse
Check out the refreshed revision resources for GCSE Maths: Calculating the hypotenuse, with step-by-step slideshows, quizzes, practice exam questions, and more!
To calculate the length of the The longest side of a right-angled triangle, which is opposite the right angle, is called the hypotenuse., use Pythagoras's theorem applies to right-angled triangles. The area of the square drawn on the hypotenuse is equal to the sum of the squares drawn on the other two sides. .
Example
Calculate the length of the hypotenuse BC.
\(a^2 + b^2 = c^2\)
\(8^2 + 15^2 = c^2\)
\(289 = c^2\)
\(c = \sqrt{289}\)
\(c = 17~\text{cm}\)
Question
Calculate the length of the hypotenuse BC. Give the answer to one decimal place.
\(a^2 + b^2 = c^2\)
\(7^2 + 10^2 = c^2\)
\(149 = c^2\)
\(c = \sqrt{149}\)
\(c = 12.2~\text{cm}\)
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