is tangent to the circle with center at , .
Line segmentWhich area is larger, green or red?
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∠ D A B = 9 0 degrees since D C is tangent to the circle and ∠ D B A = 6 0 degrees, we can verify that by trigonometry:
tan ∠ D B A = a d j o p p = r 3 r = 3 , which implies that ∠ D B A = 6 0 degrees.
Let r be the radius of the circle and A B = B E = r , then the area of triangle A B C is:
A = 2 1 b h = 2 ( 3 ) r 2 .
The area of the green region is 6 1 π r 2 . Area of a sector in a circle 3 6 0 6 0 π r 2 .
The area of the red region is 2 3 r 2 − 6 π r 2 = Area of a triangle - Area of the green sector.
Since 6 π r 2 > 2 3 r 2 − 6 π r 2 . Take 6 π = 0 . 5 2 4 and 2 3 − 6 π = 0 . 3 4 2 .
which means that 6 π > 2 3 − 6 π and 6 π r 2 > ( 2 3 − 6 π ) r 2 .
This means that the green area is larger.