Question

What is the length of the longest side of a right-angled triangle with sides 4 and 8?

• A. $4\sqrt{5}$ units
• B. $5\sqrt{4}$ units
• C. $4\sqrt{6}$ units
• D. $\sqrt{5}$ units

Answer 1

The correct option is A $4\sqrt{5}$ units

In a right-angled triangle, the longest side is its hypotenuse.
Therefore, using Pythagoras Theorem, the hypotenuse is $\sqrt{4^2+8^2}$
$=\sqrt{16+64}$
$=\sqrt{80}$

Therefore, the hypotenuse is $4\sqrt{5}$ units.