How do you find a missing side length in a right-angled triangle?

Use Pythagoras' theorem. a2 + b2 = c2. The longest side of the triangle is the hypotenuse, and it is the side opposite the right angle. We use the length of this side as 'c' if we have it. 'a' and 'b' are the other two sides, and it doesn't matter which is which.We can rearrange the above equation as c2 - b2 = a2 OR c2 - a2 = b2. This allows us to find the missing side using the equation above if we need to find the hypotenuse, or one of these other two equations if looking for a shorter side. Remember to square root at the end to find the side length.

JD

Related Maths GCSE answers

All answers ▸

How many 4 digit numbers are such that the first digit is non-zero and it is overall a multiple of 5?


Over a year, the number of rabbits in a field increases by 25% and then by a further 30%. Originally there were 200 rabbits in the field how many were there at the end?


A rectangle has an area of 20cm^2. Its length and width are enlarged by a factor of 3. Find the area of the enlarged rectangle.


The nth term of a sequence is 7n-4. Write down the 4th term and the 10th term of the sequence. The first four terms of a different sequence are 9, 13, 17, 21. Find an expression for the nth term of this sequence.