# 7 9 15 triangle

### Obtuse scalene triangle.

Sides: a = 7   b = 9   c = 15

Area: T = 20.69326919467
Perimeter: p = 31
Semiperimeter: s = 15.5

Angle ∠ A = α = 17.85219455267° = 17°51'7″ = 0.31215752273 rad
Angle ∠ B = β = 23.2132754908° = 23°12'46″ = 0.40551390016 rad
Angle ∠ C = γ = 138.9355299565° = 138°56'7″ = 2.42548784247 rad

Height: ha = 5.91221976991
Height: hb = 4.59883759882
Height: hc = 2.75990255929

Median: ma = 11.86438105177
Median: mb = 10.80550913925
Median: mc = 2.95880398915

Inradius: r = 1.33550123837
Circumradius: R = 11.41770742313

Vertex coordinates: A[15; 0] B[0; 0] C[6.43333333333; 2.75990255929]
Centroid: CG[7.14444444444; 0.92196751976]
Coordinates of the circumscribed circle: U[7.5; -8.60881115236]
Coordinates of the inscribed circle: I[6.5; 1.33550123837]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 162.1488054473° = 162°8'53″ = 0.31215752273 rad
∠ B' = β' = 156.7877245092° = 156°47'14″ = 0.40551390016 rad
∠ C' = γ' = 41.06547004347° = 41°3'53″ = 2.42548784247 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.