# 10 13 18 triangle

### Obtuse scalene triangle.

Sides: a = 10   b = 13   c = 18

Area: T = 63.52990287979
Perimeter: p = 41
Semiperimeter: s = 20.5

Angle ∠ A = α = 32.88769467704° = 32°53'13″ = 0.57439855021 rad
Angle ∠ B = β = 44.90105279607° = 44°54'2″ = 0.78436620488 rad
Angle ∠ C = γ = 102.2132525269° = 102°12'45″ = 1.78439451027 rad

Height: ha = 12.70658057596
Height: hb = 9.77436967381
Height: hc = 7.05987809775

Median: ma = 14.88328760661
Median: mb = 13.02988142208
Median: mc = 7.31443694192

Inradius: r = 3.09989770145
Circumradius: R = 9.20883888432

Vertex coordinates: A[18; 0] B[0; 0] C[7.08333333333; 7.05987809775]
Centroid: CG[8.36111111111; 2.35329269925]
Coordinates of the circumscribed circle: U[9; -1.94879284091]
Coordinates of the inscribed circle: I[7.5; 3.09989770145]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 147.113305323° = 147°6'47″ = 0.57439855021 rad
∠ B' = β' = 135.0999472039° = 135°5'58″ = 0.78436620488 rad
∠ C' = γ' = 77.78774747311° = 77°47'15″ = 1.78439451027 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.