4. a bird left its post and
flew in a triangular path. it
flew 21 yards south, 72
yards east and 75 yards
diagonally to end back at
the post. is it a right triangle?

It is a right triangle

Explanation:

We are given the directions in which a bird flew to make a triangle.

We are required to determine whether the triangle is right angle.

What is a right triangle?

Then, a² + b² = c²

In this case;

Taking the legs as a= 21 yards and b = 72 yards and the hypotenuse, c = 75 yards.

Then we can determine whether it is a right triangle;

a² = 21² = 441

b²= 72² = 5184

c² = 75² = 5625

a² + b² = 5625

Therefore; a² + b² = c²

Hence, the triangle is right triangle.

the answer is either b or c