Question

To prove the construction of ${60}^{\circ }$ angle we use the concept of _____ triangle.

• A. scalene
• B. equilateral
• C. right-angled
• D. isosceles

Answer 1

The correct option is B equilateral


In $△OBC$
OB = OC [radii of same arc]
OB = BC [Arcs of equal radius]
Then OB = OC = BC [Same arc with same radii]
$\therefore$ $△OBC$ is equilateral triangle. (All sides are equal.)
$\Rightarrow$ $\angle BOC$ = 60° (each angle of an equilateral triangle.)

$\therefore$ $\angle BOC$ = ${60}^{\circ }$.