# 15 18 30 triangle

### Obtuse scalene triangle.

Sides: a = 15   b = 18   c = 30

Area: T = 102.5911118037
Perimeter: p = 63
Semiperimeter: s = 31.5

Angle ∠ A = α = 22.33216450092° = 22°19'54″ = 0.39897607328 rad
Angle ∠ B = β = 27.12767531173° = 27°7'36″ = 0.47334511573 rad
Angle ∠ C = γ = 130.5421601874° = 130°32'30″ = 2.27883807635 rad

Height: ha = 13.67988157382
Height: hb = 11.39990131152
Height: hc = 6.83994078691

Median: ma = 23.57443504683
Median: mb = 21.94331082575
Median: mc = 7.03656236397

Inradius: r = 3.25768608901
Circumradius: R = 19.73985508488

Vertex coordinates: A[30; 0] B[0; 0] C[13.35; 6.83994078691]
Centroid: CG[14.45; 2.2879802623]
Coordinates of the circumscribed circle: U[15; -12.83300580517]
Coordinates of the inscribed circle: I[13.5; 3.25768608901]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.6688354991° = 157°40'6″ = 0.39897607328 rad
∠ B' = β' = 152.8733246883° = 152°52'24″ = 0.47334511573 rad
∠ C' = γ' = 49.45883981265° = 49°27'30″ = 2.27883807635 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.