On the formula of circle, sector area, triangle in circle,

On the formula of circle, sector area, triangle in circle,

Radius of circle = R diameter = D
Pi = 3.14159 The value of π is usually 3.14
(circle area) s circle = π * r * r (circumference) s circle = π D
S sector = (LR) / 2 (L is sector arc length)
That is arc length * radius / 2
A triangle in a circle?