» Triangle Calculator


Triangle calculator: solve triangle sides and angles, then calculate area, perimeter, heights, medians, inradius, and circumradius from common input combinations.

Use this triangle calculator to solve a triangle from common side and angle combinations and calculate sides, angles, perimeter, area, and other key measures. It works well as a triangle solver, triangle sides calculator, and triangle angle calculator for geometry, trigonometry, and construction layout checks.

Enter any valid set of three known values, such as three sides, two sides and an angle, or one side and two angles, and the calculator completes the remaining triangle properties. It also shows heights, medians, inradius, and circumradius, which makes it useful when you need more than just the perimeter or area.

3 / 6
Side (a, b, c)
Angle (α, β, γ)
°
°
°
Area
6
Perimeter
12
Semiperimeter
6
Heights
ha
4
hb
3
hc
2.4
Radii
r
Inradius
1
R
Circumradius
2.5
Medians
ma
4.27
mb
3.61
mc
2.5

Triangle Calculator FAQs

What does this triangle calculator solve?
This triangle calculator solves missing triangle values from common combinations of three known inputs. It can calculate sides, angles, perimeter, area, heights, medians, inradius, and circumradius.

Can I use it as a triangle sides calculator?
Yes. If your known values are enough to define a valid triangle, the calculator can solve the missing side lengths. Common cases include three sides, two sides and one angle, or one side and two angles.

Can I use it as a triangle angle calculator?
Yes. The calculator can find missing triangle angles when the given sides or side-angle combination determines a unique triangle. For example, if you know all three sides, it calculates the three interior angles automatically.

How do I calculate the perimeter of a triangle?
Add the three side lengths: P = a + b + c. This page works as a triangle perimeter calculator because it first solves any missing side lengths and then adds them to get the perimeter.

How do I solve a triangle from sides and angles?
Enter any valid set of three known values. The calculator supports side-side-side, side-side-angle, side-angle-angle, and other standard cases. Once the known values define a valid triangle, it computes the remaining sides, angles, and derived measures.

How do you calculate the area of a triangle?
The area depends on the available inputs. Common formulas include A = base x height / 2, Heron's formula for three sides, and trigonometric formulas such as A = ab sin(C) / 2. The calculator picks the right method from the values you enter.

Why does a triangle sometimes have two solutions or no solution?
In the side-side-angle case, the known values can produce two possible triangles, one triangle, or no triangle. The calculator shows the two-solution choice when that ambiguous case occurs and shows an alert when the given measurements do not form a valid triangle.

When is a triangle calculator useful?
It is useful for schoolwork, trigonometry, land measurement, roof and frame layout, CAD checks, and any problem where you need to solve a triangle from a partial set of sides and angles.


Ages 2–5
Free right now
Free Toddler Learning, No Ads
TeddyBase learning app for toddlers
ABC, numbers, colours, animals, time and weekdays in simple tap-and-listen lessons.
No ads No in-app purchases No data collection
Download on the App Store
Stainless steel grill tongs holding grilled meat
BBQ essential
Keep Your Hands Away From the Heat
Long stainless-steel tongs for steaks, ribs, vegetables, and hot grill food.
14 inch reach · Locking handle
See it on Amazon