Answer:
b- If two sides are perpendicular, then it is a right triangle. It can be isosceles or scalene. It cannot be equilateral because all the angles in an equilateral triangle are acute.
Explanation:
An equilateral triangle has 3 equal sides and 3 congruent angles, each with an acute measure of 60 deg.
If two sides are perpendicular, they form a right angle, w/ measure of 90 deg. Therefore, cannot be equilateral.
30-60-90 triangles are quite common and useful in geometry... they are scalene and have 2 perpendicular sides.
45-45-90 triangles are isosceles and have 2 perpendicular sides.
Both are types of right triangles.