# 9 21 25 triangle

### Obtuse scalene triangle.

Sides: a = 9   b = 21   c = 25

Area: T = 90.92440754696
Perimeter: p = 55
Semiperimeter: s = 27.5

Angle ∠ A = α = 20.26659019313° = 20°15'57″ = 0.35437067146 rad
Angle ∠ B = β = 53.92218000282° = 53°55'18″ = 0.94111129491 rad
Angle ∠ C = γ = 105.8122298041° = 105°48'44″ = 1.84767729899 rad

Height: ha = 20.20553501044
Height: hb = 8.6599435759
Height: hc = 7.27439260376

Median: ma = 22.64439837484
Median: mb = 15.58804364509
Median: mc = 10.23547447452

Inradius: r = 3.30663300171
Circumradius: R = 12.9921608591

Vertex coordinates: A[25; 0] B[0; 0] C[5.3; 7.27439260376]
Centroid: CG[10.1; 2.42546420125]
Coordinates of the circumscribed circle: U[12.5; -3.54400414944]
Coordinates of the inscribed circle: I[6.5; 3.30663300171]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 159.7344098069° = 159°44'3″ = 0.35437067146 rad
∠ B' = β' = 126.0788199972° = 126°4'42″ = 0.94111129491 rad
∠ C' = γ' = 74.18877019595° = 74°11'16″ = 1.84767729899 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.