# 3 17 18 triangle

### Obtuse scalene triangle.

Sides: a = 3   b = 17   c = 18

Area: T = 24.65876560119
Perimeter: p = 38
Semiperimeter: s = 19

Angle ∠ A = α = 9.27442999592° = 9°16'27″ = 0.16218670701 rad
Angle ∠ B = β = 65.95879240942° = 65°57'29″ = 1.15111829432 rad
Angle ∠ C = γ = 104.7687775947° = 104°46'4″ = 1.82985426403 rad

Height: ha = 16.43884373413
Height: hb = 2.90109007073
Height: hc = 2.74397395569

Median: ma = 17.44327635425
Median: mb = 9.70882439195
Median: mc = 8.24662112512

Inradius: r = 1.2987771369
Circumradius: R = 9.30774540374

Vertex coordinates: A[18; 0] B[0; 0] C[1.22222222222; 2.74397395569]
Centroid: CG[6.40774074074; 0.9133246519]
Coordinates of the circumscribed circle: U[9; -2.3722488284]
Coordinates of the inscribed circle: I[2; 1.2987771369]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 170.7265700041° = 170°43'33″ = 0.16218670701 rad
∠ B' = β' = 114.0422075906° = 114°2'31″ = 1.15111829432 rad
∠ C' = γ' = 75.23222240535° = 75°13'56″ = 1.82985426403 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.