Question

While drawing a perpendicular to a given line through a point nearer to the end of the line, which of the following properties of the circle is used?

(a) The diameter of a circle always subtends an angle of 90˚ on the circumference

(b) The angle at the circumference is half the angle at the centre of the circle

(c) The summation of the opposite angles of a quadrilateral is always 180˚

(d) In an arc the angle subtended by any two points on the circumference is always same

This question was posed to me in class test.

This question is from Construction of Parallel & Perpendicular Lines in division Geometrical Construction of Engineering Drawing

Answer 1

Right choice is (a) The diameter of a circle always subtends an angle of 90˚ on the circumference

To explain I would say: While drawing a perpendicular to a given line through a point nearer to the end of the line, the geometric property of the circle that the diameter of a circle always subtends an angle of 90˚ on the circumference of the circle is used to draw the perpendicular line.