Let circle inscribed in equilateral triangle

Be with centre O and radius ‘r’

Area of circle = πr^{2}

But given that area = 154 cm^{2}.

πr^{2} = 154

22/7xr^{2}=154

r^{2}=7×7

r = 7cms

Radius of circle = 7cms

From fig. at point M, BC side is tangent at point M, BM ⊥ OM. In equilateral triangle, the perpendicular from vertex divides the side into two halves

ΔBMO is right triangle, by Pythagoras theorem