# 15 21 26 triangle

### Obtuse scalene triangle.

Sides: a = 15   b = 21   c = 26

Area: T = 157.488015748
Perimeter: p = 62
Semiperimeter: s = 31

Angle ∠ A = α = 35.22993196511° = 35°13'46″ = 0.61548676211 rad
Angle ∠ B = β = 53.86111853369° = 53°51'40″ = 0.94400550232 rad
Angle ∠ C = γ = 90.9099495012° = 90°54'34″ = 1.58766700093 rad

Height: ha = 20.99773543307
Height: hb = 14.99881102362
Height: hc = 12.11438582677

Median: ma = 22.4110934831
Median: mb = 18.44658667457
Median: mc = 12.80662484749

Inradius: r = 5.088000508
Circumradius: R = 13.00216380016

Vertex coordinates: A[26; 0] B[0; 0] C[8.84661538462; 12.11438582677]
Centroid: CG[11.61553846154; 4.03879527559]
Coordinates of the circumscribed circle: U[13; -0.20663752064]
Coordinates of the inscribed circle: I[10; 5.088000508]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 144.7710680349° = 144°46'14″ = 0.61548676211 rad
∠ B' = β' = 126.1398814663° = 126°8'20″ = 0.94400550232 rad
∠ C' = γ' = 89.0910504988° = 89°5'26″ = 1.58766700093 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.