Assertion: circle's area | /r/CapableOf | enclose by circle
Facets:
Source sentences:
text: Another proof that uses triangles considers the area enclosed by a circle to be made up of an infinite number of triangles (i.e. the triangles each have an angle of dθ at the centre of the circle), each with an area of 1/2 · r2 · dθ (derived from the expression for the area of a triangle: 1/2 · a · b · sinθ = 1/2 · r · r · sin(dθ) = 1/2 · r2 · dθ).