An obtusage triangle is a triangle via one internal angle meacertain better than 90 levels. In geometry, triangles are considered as 2D closed figures through three sides of the same or various lengths and three angles with the same or different dimensions. Based on the length, angles, and also properties, tright here are six kinds of triangles that we learn in geomeattempt i.e. scalene triangle, best triangle, acute triangle, obtuse triangle, isosceles triangle, and also equilateral triangle.

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If among the internal angles of the triangle is more than 90°, then the triangle is referred to as the obtuse-angled triangle. Let's learn more around obtuse triangles, their properties, the formulas required, and also resolve a couple of examples to understand also the principle better.

1.What Is an Obtusage Triangle?
2.Obtusage Angled Triangle Formula
3.Obtusage Angled Triangle Properties
4.FAQs on Obtuse Triangles

What Is an Obtuse Triangle?

An obtuse-angled triangle or obtuse triangle is a kind of triangle whose one of the vertex angles is bigger than 90°. An obtuse-angled triangle has among its vertex angles as obtuse and also other angles as acute angles i.e. if one of the angles measure more than 90°, then the sum of the other two angles is much less than 90°. The side oppowebsite to the obtusage angle is considered the longest. For instance, in a triangle ABC, three sides of a triangle meacertain a, b, and also c, c being the longest side of the triangle as it is the oppowebsite side to the obtusage angle. Hence, the triangle is an obtuse-angled triangle wbelow a2 + b2 2

An obtuse-angled triangle have the right to be a scalene triangle or isosceles triangle but will never before be equilateral because an equilateral triangle has equal sides and also angles wright here each angle actions 60°. Similarly, a triangle cannot be both an obtuse and a right-angled triangle since the best triangle has actually one angle of 90° and the other two angles are acute. As such, a right-angle triangle cannot be an obtuse triangle and vice versa. Centroid and also incenter lie within the obtuse-angled triangle while circumfacility and also orthocenter lie outside the triangle.

The triangle listed below has actually one angle greater than 90°. Thus, it is referred to as an obtuse-angled triangle or sindicate an obtuse triangle.


Obtusage Angled Triangle Formula

There are separate formulregarding calculate the perimeter and also the area of an obtusage triangle. Let's learn each of the formulas in information.

Obtusage Triangle Perimeter

The perimeter of an obtusage triangle is the amount of the measures of all its sides. Hence, the formula for the perimeter of an obtuse-angled triangle is:

Perimeter of obtuse angled triangle = (a + b + c) units.

Area of Obtusage Triangle

To discover the location of an obtuse triangle, a perpendicular line is built external of the triangle wright here the elevation is acquired. Due to the fact that an obtuse triangle has actually a value of one angle even more than 90°. Once the elevation is acquired, we can discover the area of an obtusage triangle by using the formula discussed below.

In the given obtuse triangle ΔABC, we know that a triangle has 3 altitudes from the three vertices to the oppowebsite sides. The altitude or the height from the acute angles of an obtusage triangle lies outside the triangle. We extend the base as presented and determine the height of the obtusage triangle


Area of ΔABC = 1/2 × h × b where BC is the base, and also h is the height of the triangle.

Area of an Obtuse-Angled Triangle = 1/2 × Base × Height

Obtuse Triangle Area by Heron's Formula

The area of an obtuse triangle deserve to additionally be discovered by utilizing Heron's formula. Consider the triangle ΔABC through the size of the sides a, b, and also c.

Heron's formula to discover the area of an obtuse triangle is: (sqrt s(s - a)(s - b)(s - c)), wright here, (a + b + c) is the perimeter of the triangle and also S is the semi-perimeter which is provided by (s): = (a + b + c)/2

Properties of Obtuse-Angled Triangles

Each triangle has actually its very own properties that specify them. An obtuse triangle has four different properties. Let's view what they are:

Property 1: The longest side of a triangle is the side opposite to the obtuse angle. Consider the ΔABC, side BC is the longest side which is oppowebsite to the obtuse angle ∠A. See the image listed below for referral.


Property 2: A triangle deserve to only have actually one obtuse angle. We understand that the angles of a triangle amount up to 180°. Consider the obtusage triangle displayed listed below. We deserve to observe that among the angles steps better than 90°, making it an obtuse angle. For circumstances, if among the angles is 91°, the sum of the various other 2 angles will be 89°. Hence, a triangle cannot have actually 2 obtuse angles because the sum of all the angles cannot exceed 180 degrees. Observe the photo provided below to understand the very same through an illustration.


Property 3: The amount of the various other two angles in an obtusage triangle is constantly smaller sized than 90°. We simply learned that as soon as one of the angles is an obtusage angle, the various other 2 angles include approximately much less than 90°.


In the over triangle, ∠1 > 90°. We know that by angle amount property, the amount of the angles of a triangle is 180°. Because of this, ∠1 + ∠2 + ∠3 = 180° and also ∠1 > 90°

Subtracting the over two, we have actually, ∠2 + ∠3 As viewed in the picture below:


Circumfacility (H), the median suggest from all the triangle vertices, lies exterior in an obtuse triangle. As viewed in the image below:


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Example 2: Find the height of the given obtuse-angled triangle whose area = 60 in2 and base = 8 in.



Area of an obtuse-angled triangle = 1/2 × base × height. As such, the elevation of the obtuse triangle can be calculated by:

Height = (2 × Area)/base

Substituting the values, we get:

Height = (2 × 60)/8 = 15 inches

Thus, the height of the given obtuse triangle is 15 inches.

Example 3: Can sides measuring 3 inches, 4 inches, and also 6 inches form an obtusage triangle?


The sides of an obtuse triangle have to meet the condition that the sum of the squares of any two sides is lesser than the square of the third side.

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We know that

a = 3 in

b = 4 in

c = 6 in

Taking the squares of the sides, we get: a2 = 9, b2 = 16, and also c2 = 36

We know that, a2 + b2 2

36 > (9 + 16)

The provided steps have the right to create the sides of an obtuse triangle. Because of this, 3 inches, 4 inches, and 6 inches can be the sides of an obtuse triangle.