Homepage Show Accessibility links
BBC Account Notifications
More menu Search Bitesize Search Bitesize
BITESIZE
GCSE OCR Pythagoras' theoremPythagoras’ theorem can be used to calculate the length of any side in a right-angled triangle. Pythagoras’ theorem can be applied to solve 3-dimensional problems. Part of Maths Geometry and measure
video Videoquiz Test
Calculating the length of one of the shorter sidesRearrange Pythagoras' theorem to calculate the length of one of the shorter sides. \(a^2 + b^2 = c^2\) calculates the length of the longest side. To calculate the length of one of the shorter sides, rearrange the formula to make \(a^2\) or \(b^2\) the subject. \(a^2 = c^2 - b^2\) or \(b^2 = c^2 - a^2\) Then take the square root to calculate the length \(a\) or \(b\). ExampleCalculate the length AB. \[a^2 + b^2 = c^2\] \[8^2 + b^2 = 10^2\] Rearrange the formula to make \(b^2\) the subject: \[b^2 = 10^2 - 8^2\] \[b^2 = 36\] \[b = \sqrt{36}\] \[b = 6~\text{cm}\] The length AB is 6 cm. QuestionCalculate the length AO. Give the answer to one decimal place. \[a^2 + b^2 = c^2\] \[3^2 + b^2 = (\sqrt{17})^2\] Rearrange the formula to make \(b^2\) the subject. \[b^2 = (\sqrt{17})^2 - 3^2\] \[b^2 = 17 - 9\] \[b^2 = 8\] \[b = \sqrt{8}\] \[b = 2.8~\text{cm}\] The length AO is 2.8 cm.
GCSE Subjects
What is the shortest side of a triangle?The shortest side of a triangle is always opposite the smallest angle. For example, in ∆ABC below, side BC is the shortest side and is opposite angle A.
What is the 3 4 5 Triangle rule?The 3:4:5 triangle is the best way I know to determine with absolutely certainty that an angle is 90 degrees. This rule says that if one side of a triangle measures 3 and the adjacent side measures 4, then the diagonal between those two points must measure 5 in order for it to be a right triangle.
|