The perimeter of a shape is the sum of its side lengths.
<em>Joshua miscalculated the third length of the triangle</em>
First, we calculate the third length (x) of the triangle.
Because the triangle is right-angled, we can make use of Pythagoras.
So we have:
Take square roots of both sides
The other shape in the figure is a square.
So, the perimeter (P) is
---- i.e. the sum of the visible lengths
So, we have:
Evaluate like terms:
Hence, Joshua's error is that:
<em>He miscalculated the third length of the triangle</em>
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