Question

The base diameter of a conical helix is 100 mm and other end diameter is 80 mm. The height of helix is 50 mm. What is the angle between the base and slanting side is?

(a) 58 degrees

(b) 79 degrees

(c) 89 degrees

(d) 45 degrees

The question was asked in unit test.

Query is from Helix upon a Cone topic in division Curves used in Engineering Practice of Engineering Drawing

Answer 1

Correct choice is (a) 58 degrees

For explanation: Base radius= 50 mm. Other end radius = 40 mm. 50 mm– 40mm = 10 mm. height is 50 mm. tan (angle) = height/ base radius = 50 mm/10 mm = 5. Angle = tan-1(5) = 78.69 degrees approximately equals to 79 degrees.