# 12 17 18 triangle

### Acute scalene triangle.

Sides: a = 12   b = 17   c = 18

Area: T = 98.29326116247
Perimeter: p = 47
Semiperimeter: s = 23.5

Angle ∠ A = α = 39.9743659556° = 39°58'25″ = 0.69876719733 rad
Angle ∠ B = β = 65.52114938607° = 65°31'17″ = 1.14435657987 rad
Angle ∠ C = γ = 74.50548465832° = 74°30'17″ = 1.33003548816 rad

Height: ha = 16.38221019374
Height: hb = 11.56438366617
Height: hc = 10.92114012916

Median: ma = 16.44768842034
Median: mb = 12.7188097342
Median: mc = 11.64404467268

Inradius: r = 4.18326643245
Circumradius: R = 9.33994608692

Vertex coordinates: A[18; 0] B[0; 0] C[4.97222222222; 10.92114012916]
Centroid: CG[7.65774074074; 3.64404670972]
Coordinates of the circumscribed circle: U[9; 2.49551010655]
Coordinates of the inscribed circle: I[6.5; 4.18326643245]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 140.0266340444° = 140°1'35″ = 0.69876719733 rad
∠ B' = β' = 114.4798506139° = 114°28'43″ = 1.14435657987 rad
∠ C' = γ' = 105.4955153417° = 105°29'43″ = 1.33003548816 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.