(i) Straight angle – It is formed when legs are pointing in opposite direction and they form a straight line through the vertex of the angle. Thus measure of a straight line is always 180°.

Let’s discuss revolution a revolution is a complete turn or a full rotation so it points back the same way and form an angle of 360°. And a straight angle is the half of the revolution that is 180°.

(ii) Right angle is of 90° and 90° is the of the 360°

(iii) Acute angle is less than 90° so it will be less than one-fourth of a revolution as 90° is the one-fourth.

(iv) Obtuse angle is the angle greater than 90° but less than 180° so it will be in between one-fourth and half of the revolution.

(v) Reflex angle whose measure is greater than 180° but less than 360° so it is more than half a revolution.