If he travels 12km/h for 3 hours then he went 36km in 3hr. The answer is 36km.
An isosceles triangle is a triangle with two equal sides. Since, one of the angles is 90 degrees. Then, the 2 remaining must equal 90 because the total of the triangle should be 180 degrees. So, I think 45 degrees is the only one we can use here because 45 + 45 = 90 degrees.
