# 9 15 18 triangle

### Obtuse scalene triangle.

Sides: a = 9   b = 15   c = 18

Area: T = 67.35498329619
Perimeter: p = 42
Semiperimeter: s = 21

Angle ∠ A = α = 29.92664348666° = 29°55'35″ = 0.52223148218 rad
Angle ∠ B = β = 56.25110114041° = 56°15'4″ = 0.98217653566 rad
Angle ∠ C = γ = 93.82325537293° = 93°49'21″ = 1.63875124752 rad

Height: ha = 14.96766295471
Height: hb = 8.98799777283
Height: hc = 7.48333147735

Median: ma = 15.94552187191
Median: mb = 12.09333866224
Median: mc = 8.48552813742

Inradius: r = 3.20771349029
Circumradius: R = 9.02200669145

Vertex coordinates: A[18; 0] B[0; 0] C[5; 7.48333147735]
Centroid: CG[7.66766666667; 2.49444382578]
Coordinates of the circumscribed circle: U[9; -0.60113377943]
Coordinates of the inscribed circle: I[6; 3.20771349029]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 150.0743565133° = 150°4'25″ = 0.52223148218 rad
∠ B' = β' = 123.7498988596° = 123°44'56″ = 0.98217653566 rad
∠ C' = γ' = 86.17774462707° = 86°10'39″ = 1.63875124752 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.