Question

a weathervane is pointing north. after the wind changes direction, the weathervane points eas
the turn forms a right angle.
how many degrees did the arrow turn?

Explanation:

Step1: Recall right angle definition

A right angle is defined as an angle of $90^\circ$.

Step2: Relate to weathervane turn

The weathervane turns from North to East, and the turn forms a right angle. So the number of degrees the arrow turned is equal to the measure of a right angle.

Answer:

$90$