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Chapter overview
Learning goals
Learning Goals
Maths
Summary
So far, you have used Pythagoras' theorem to find lengths of 2 dimensional shapes. However, Pythagoras' theorem can also applied to find distances in 3 dimensions.
It is best to show this with a sketch. Here is a cuboid ABCDEFGH:
To find the distance AF (=d), first use Pythagoras' theorem on triangle ABH to find the distance AH, and then use it again on triangle AFH to find the distance AF.
In the cuboid shown above, a=3cm,b=4cm,d=13cm. Find the value of c.
Find AH by focusing on the right-angled triangle ABH:
a2+b2=(AH)2
32+42=(AH)2
(AH)2=25
AH=25=5cm
Then, find c by focusing