Plane figures {triangle} can have three sides.
area
Triangle area equals 0.5 * b * h, where b is base and h is height.
Triangle area = r*s, where r is inscribed-circle radius, s is (a + b + c) / 2, and a, b, c are sides.
Triangle area = c^2 * sin(A) * sin(B) / (2 * sin(C)), where c is side length, and A, B, C are opposite angles to sides a, b, c.
Triangle area = 0.5 * b * c * sin(A), where b is base length, c is side length, and A is angle between base and side.
area: isosceles
Isosceles-triangle area = 0.5 * b * a * sin(A), where b is base length, a is equal-side length, and A is base angle.
area: equilateral
Equilateral-triangle area = 3^(0.5) * s / 2, where s is side length.
angle sum
Triangle angle sum is 180 degrees.
triangle perimeter
Triangle perimeter = a + b + c, where a, b, c are side lengths. Isosceles-triangle perimeter = 2*a + b, where a is equal-side length, and b is other-side length. Equilateral triangle perimeter = 3*s, where s is side length.
Mathematical Sciences>Geometry>Plane>Polygon>Kinds>Triangle
3-Geometry-Plane-Polygon-Kinds-Triangle
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Date Modified: 2022.0224