# 7 18 23 triangle

### Obtuse scalene triangle.

Sides: a = 7   b = 18   c = 23

Area: T = 49.47772675074
Perimeter: p = 48
Semiperimeter: s = 24

Angle ∠ A = α = 13.82987435443° = 13°49'43″ = 0.24113571063 rad
Angle ∠ B = β = 37.92546365774° = 37°55'29″ = 0.66219097759 rad
Angle ∠ C = γ = 128.2476619878° = 128°14'48″ = 2.23883257714 rad

Height: ha = 14.1366362145
Height: hb = 5.49774741675
Height: hc = 4.30223710876

Median: ma = 20.3533132437
Median: mb = 14.42222051019
Median: mc = 7.36554599313

Inradius: r = 2.06215528128
Circumradius: R = 14.64330883616

Vertex coordinates: A[23; 0] B[0; 0] C[5.52217391304; 4.30223710876]
Centroid: CG[9.50772463768; 1.43441236959]
Coordinates of the circumscribed circle: U[11.5; -9.06547689857]
Coordinates of the inscribed circle: I[6; 2.06215528128]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.1711256456° = 166°10'17″ = 0.24113571063 rad
∠ B' = β' = 142.0755363423° = 142°4'31″ = 0.66219097759 rad
∠ C' = γ' = 51.75333801217° = 51°45'12″ = 2.23883257714 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    