Question Detail
Question
If a cone is formed by rotating a right-angled triangle with an apex and angled θ, what is the apex angle of the cone?
Correct Answer
Option B is the correct answer.
Detailed Explanation
Page 2 states: 'The apex angle of a cone is 2θ.' This refers to the angle of the original right-angled triangle at the apex before rotation. When rotated about the altitude, the full angle at the cone's apex will be twice this angle.
Hint
The rotation creates a symmetrical shape, effectively doubling the initial angle to form the full cone's apex angle.