Triangle Types:
Isosceles Triangle: Two sides are equal. If b=c, then A=B.
Equilateral Triangle: All sides are equal. A=B=C.
Scalene Triangle: All sides are different. A≠B≠C.
Obtuse Triangle: One angle is greater than 90°. The longest side is opposite the obtuse angle.
Acute Triangle: All angles are less than 90°. The longest side is opposite the largest angle.
Right Triangle: One angle is 90°. It follows the Pythagorean theorem: a^2 + b^2 = c^2.
Triangle Calculator Online
Online Triangle Formulas
Common Triangle Formulas:
Heron's Formula for Area: A = √[s(s - a)(s - b)(s - c)], where s = (a + b + c)/2
Area By Base and Height: A = (1/2) × Base × Height
Area By Two Sides and Included Angle: A = (1/2) × a × b × sin(C)
TrianglePerimeter: P = a + b + c
Isosceles Triangle:
Area: A = (1/2) × Base × Height
Side Lengths: a = b, c ≠ a
Equilateral Triangle:
Area: A = (√3/4) × side^2
Side Lengths: a = b = c
Scalene Triangle:
Area: A = √[s(s - a)(s - b)(s - c)], where s = (a + b + c)/2
Side Lengths: a ≠ b ≠ c
Obtuse Triangle:
Area: A = √[s(s - a)(s - b)(s - c)], where s = (a + b + c)/2
Angle: One angle > 90°
Acute Triangle:
Area: A = √[s(s - a)(s - b)(s - c)], where s = (a + b + c)/2
Angles: All angles < 90°
Right Triangle:
Area: A = (1/2) × Base × Height
Pythagorean Theorem: a^2 + b^2 = c^2
Formula to Calculate Triangle Height by Base and Area:
Height: h = (2 × Area) / Base
Formula to Calculate Triangle Angle in Degrees by Area, Base, and Side:
Angle: Angle (in degrees) = arcsin[(2 × Area) / (Base × Side)]
Formula to Calculate Triangle Sides by Base, Height, and Angle:
Side: Side = √(Base^2 + Height^2)
Side: Side = Height / tan(Angle)
