# 10 15 20 triangle

### Obtuse scalene triangle.

Sides: a = 10   b = 15   c = 20

Area: T = 72.61884377414
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 28.95550243719° = 28°57'18″ = 0.50553605103 rad
Angle ∠ B = β = 46.56774634422° = 46°34'3″ = 0.81327555614 rad
Angle ∠ C = γ = 104.4787512186° = 104°28'39″ = 1.82334765819 rad

Height: ha = 14.52436875483
Height: hb = 9.68224583655
Height: hc = 7.26218437741

Median: ma = 16.95658249578
Median: mb = 13.91994109071
Median: mc = 7.90656941504

Inradius: r = 3.22774861218
Circumradius: R = 10.32879555899

Vertex coordinates: A[20; 0] B[0; 0] C[6.875; 7.26218437741]
Centroid: CG[8.95883333333; 2.42106145914]
Coordinates of the circumscribed circle: U[10; -2.58219888975]
Coordinates of the inscribed circle: I[7.5; 3.22774861218]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 151.0454975628° = 151°2'42″ = 0.50553605103 rad
∠ B' = β' = 133.4332536558° = 133°25'57″ = 0.81327555614 rad
∠ C' = γ' = 75.52224878141° = 75°31'21″ = 1.82334765819 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.