# 15 16 18 triangle

### Acute scalene triangle.

Sides: a = 15   b = 16   c = 18

Area: T = 113.3999459875
Perimeter: p = 49
Semiperimeter: s = 24.5

Angle ∠ A = α = 51.95221438479° = 51°57'8″ = 0.90767359636 rad
Angle ∠ B = β = 57.14396971359° = 57°8'23″ = 0.99772758486 rad
Angle ∠ C = γ = 70.90881590162° = 70°54'29″ = 1.23875808414 rad

Height: ha = 15.12199279834
Height: hb = 14.17549324844
Height: hc = 12.65999399861

Median: ma = 15.28988848514
Median: mb = 14.50986181285
Median: mc = 12.62993309403

Inradius: r = 4.62985493827
Circumradius: R = 9.5243854886

Vertex coordinates: A[18; 0] B[0; 0] C[8.13988888889; 12.65999399861]
Centroid: CG[8.7132962963; 4.21999799954]
Coordinates of the circumscribed circle: U[9; 3.11550942023]
Coordinates of the inscribed circle: I[8.5; 4.62985493827]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 128.0487856152° = 128°2'52″ = 0.90767359636 rad
∠ B' = β' = 122.8660302864° = 122°51'37″ = 0.99772758486 rad
∠ C' = γ' = 109.0921840984° = 109°5'31″ = 1.23875808414 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.