Let a,b,c be the lengths of the sides of a triangle. The area is given by: where p is half the perimeter, or Show Try this Drag the orange dots to reshape the triangle. The formula shown will re-calculate the triangle's area using Heron's Formula Heron was one of the great mathematicians of antiquity and came up with this formula sometime in the first century BC, although it may have been known earlier. He also extended it to the area of quadrilaterals and higher-order polygons. The 3 sides triangle area calculator is here to the rescue if you need to calculate the area of a triangle but only know the three side lengths. A good example is trying to figure out the area of a triangular-shaped room – with this calculator, you'll learn how to find the square footage of a triangle room. Read on to learn about:
Calculating the area of a triangle with 3 sides – Heron's formulaTo calculate the area of a triangle using the three side lengths is surprisingly tricky. If we know the height, then the area is found by simply multiplying the height by the base length and dividing by two. What we have built is a triangle area calculator – 3 sides and without height. The area can be found using Heron's formula, first published by Heron (or Hero) of Alexandria in around 60 AD. It's believed Archimedes knew the formula 200 years earlier, but it was never published at the time, as far as we know. Heron's formula can be expressed in many ways. The longest form is to take the three sides (aaa, bbb, and ccc), sum them together, then multiply by another three sums, but each time one of the sides is subtracted. Then the square root is taken, and we divide it by four to get the area AAA. Here is that mathematically: A=14[(a+b+c)(−a+b+c)(a−b+c)(a+b−c)]\footnotesize \begin{align*} A = \frac{1}{4}\sqrt{}[(a + b + c)(-a + b + c)\\[0.5em] (a - b + c)(a + b - c)] \end{align*}A=41[(a+b+c)(−a+b+c)(a−b+c)(a+b−c)] A more compact way to write the same formula is: A=144a2b2−(a2+b2−c2)2\footnotesize A = \frac{1}{4}\sqrt{4a^2b^2 - (a^2 + b^2 - c^2)^2}A=414a2b2−(a2+b2−c2)2 All rather complicated. So why not just use our 3 side triangle area calculator to make life easy. How to use this 3 side triangle area calculatorIt's super easy to use the calculator. Simply enter the three side lengths, and the calculator will show the area result instantly. You can even try using the calculator to find a missing side length if you know the area and the other two side lengths:
And that is how to find the third side of a triangle without angles. Other triangle area calculatorsHere are some other triangle area calculators you can explore here on the Omni Calculator website:
FAQCan any 3 sides make a triangle?No, it is not the case that any 3 sides can make a triangle. If one side of the triangle is longer than the sum of the other two sides, then you cannot form a triangle. What is the rule for 3 sides of a triangle?The sides of a triangle rule asserts that the sum of the lengths of any two sides of a triangle has to be greater than the length of the third side.
How do you find the area of three sides?The area of a triangle is defined as the total region that is enclosed by the three sides of any particular triangle. Basically, it is equal to half of the base times height, i.e. A = 1/2 × b × h. Hence, to find the area of a tri-sided polygon, we have to know the base (b) and height (h) of it.
How do you find the area of a triangle?Finding area of triangles. To find a triangle's area, use the formula area = 1/2 * base * height. Choose a side to use for the base, and find the height of the triangle from that base.
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