1) question 1 has been done for you
2) step one: square the two numbers that aren’t the hypotenuse(the longest side-opposite the right angle).
Step two: add the two numbers together
Step three: square the hypotenuse
If the two values squared and added together equal the hypotenuse squared then it is a right angled triangle.
3) a triangle with the side lengths of 11cm, 13cm and 15cm wouldn’t be a right angled triangle.
Because 11^2 + 13^2 = 290 and 15^2 = 225, therefore it isn’t a right angled triangle because 290 doesn’t equal 225.