Final answer:
The size of angle 0 in the isosceles triangle is 90 degrees.
Step-by-step explanation:
To calculate the size of angle 0 in the isosceles triangle, we can use the fact that the sum of the angles in a triangle is 180 degrees. Since it is an isosceles triangle, the two base angles are equal. Let's call the base angle x. We can set up the equation: x + x + 0 = 180. Therefore, 2x + 0 = 180. Solving for x, we get x = 90 degrees. Since angle 0 is equal to angle x, we can conclude that angle 0 is also 90 degrees.