The correct option is A 4√3 cm2
Steps of construction of 60∘ angle:
Step 1 : Draw the given ray OA and taking O as centre and radius = 4 cm, draw an arc which intersects OA, say at a point B.
Step 2 : Taking B as centre and with the same radius, draw an arc intersecting the previously drawn arc at a point C.
Step 3 : Draw a ray OD Passing through C then ∠BOC is the required angle of 60°.
In △OBC
OB = OC [radii of same arc]
OB = BC [Arcs of equal radius]
Then OB = OC = BC = 4 cm. [Same arc with same radii]
∴ △OBC is equilateral triangle.
Area of an equilteral triangle
= √34×side2=√34×42
= 4√3 cm2