# 18 24 28 triangle

### Acute scalene triangle.

Sides: a = 18   b = 24   c = 28

Area: T = 214.044438792
Perimeter: p = 70
Semiperimeter: s = 35

Angle ∠ A = α = 39.57112194572° = 39°34'16″ = 0.69106480686 rad
Angle ∠ B = β = 58.1454569176° = 58°8'40″ = 1.01548141743 rad
Angle ∠ C = γ = 82.28442113668° = 82°17'3″ = 1.43661304108 rad

Height: ha = 23.78327097689
Height: hb = 17.83770323267
Height: hc = 15.28988848514

Median: ma = 24.4744476501
Median: mb = 20.24884567313
Median: mc = 15.93773774505

Inradius: r = 6.11655539406
Circumradius: R = 14.12879107076

Vertex coordinates: A[28; 0] B[0; 0] C[9.5; 15.28988848514]
Centroid: CG[12.5; 5.09662949505]
Coordinates of the circumscribed circle: U[14; 1.89768028265]
Coordinates of the inscribed circle: I[11; 6.11655539406]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 140.4298780543° = 140°25'44″ = 0.69106480686 rad
∠ B' = β' = 121.8555430824° = 121°51'20″ = 1.01548141743 rad
∠ C' = γ' = 97.71657886332° = 97°42'57″ = 1.43661304108 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    