Because the people were randomly assigned to one of the two groups, there is a randomness to both groups making them the same. The group that doesn't get the cream is a control group so any differences observed between the control and the group being tested would be due to the cream.
we know the triangle is an isosceles, so it has twin sides, and then the hypotenuse, since it's a right-triangle, we can just use the pythagorean theorem for that.