# 20 30 30 triangle

### Acute isosceles triangle.

Sides: a = 20   b = 30   c = 30

Area: T = 282.8432712475
Perimeter: p = 80
Semiperimeter: s = 40

Angle ∠ A = α = 38.9422441269° = 38°56'33″ = 0.68796738189 rad
Angle ∠ B = β = 70.52987793655° = 70°31'44″ = 1.23109594173 rad
Angle ∠ C = γ = 70.52987793655° = 70°31'44″ = 1.23109594173 rad

Height: ha = 28.28442712475
Height: hb = 18.85661808316
Height: hc = 18.85661808316

Median: ma = 28.28442712475
Median: mb = 20.61655281281
Median: mc = 20.61655281281

Inradius: r = 7.07110678119
Circumradius: R = 15.91099025767

Vertex coordinates: A[30; 0] B[0; 0] C[6.66766666667; 18.85661808316]
Centroid: CG[12.22222222222; 6.28553936105]
Coordinates of the circumscribed circle: U[15; 5.30333008589]
Coordinates of the inscribed circle: I[10; 7.07110678119]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 141.0587558731° = 141°3'27″ = 0.68796738189 rad
∠ B' = β' = 109.4711220634° = 109°28'16″ = 1.23109594173 rad
∠ C' = γ' = 109.4711220634° = 109°28'16″ = 1.23109594173 rad

# How did we calculate this triangle?

Now we know the lengths of all three sides of the triangle and the triangle is uniquely determined. Next we calculate another its characteristics - same procedure as calculation of the triangle from the known three sides SSS. ### 1. The triangle circumference is the sum of the lengths of its three sides ### 2. Semiperimeter of the triangle ### 3. The triangle area using Heron's formula ### 4. Calculate the heights of the triangle from its area. ### 5. Calculation of the inner angles of the triangle using a Law of Cosines ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.