...5. A circumference can always be passed through the angular points of a rectangle. 6. A tangent to a circle is perpendicular to the radius drawn to the point of contact. 7. If A: B=P: Q, prove B: A=Q: P. 8. All angles inscribed in the same segment of a circle are equal....
A tangent to a circle is perpendicular to the radius drawn to the point of contact. 
