An obtuse triangle is a triangle v one interior angle measure better than 90 degrees. In geometry, triangles are considered as 2D closed figures with three sides that the very same or various lengths and three angles through the exact same or different measurements. Based upon the length, angles, and also properties, over there are 6 kinds the triangles the we learn in geometry i.e. Scalene triangle, appropriate triangle, acute triangle, obtuse triangle, isosceles triangle, and equilateral triangle.

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If among the inner angles the the triangle is an ext than 90°, then the triangle is called the obtuse-angled triangle. Let's learn an ext about obtuse triangles, their properties, the recipe required, and solve a few examples to know the concept better.

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

What Is an Obtuse Triangle?

An obtuse-angled triangle or obtuse triangle is a type of triangle whose one of the vertex angles is bigger 보다 90°. An obtuse-angled triangle has one that its vertex angle as obtuse and other angle as acute angle i.e. If one of the angle measure more than 90°, climate the amount of the other two angles is less than 90°. The side opposite to the obtuse angle is considered the longest. Because that example, in a triangle ABC, three sides the a triangle measure up a, b, and also c, c gift the longest side of the triangle as it is the opposite side to the obtuse angle. Hence, the triangle is one obtuse-angled triangle whereby a2 + b2 2

An obtuse-angled triangle have the right to be a scalene triangle or isosceles triangle but will never be equilateral since an it is intended triangle has actually equal sides and angles wherein each angle measures 60°. Similarly, a triangle can not be both an obtuse and also a right-angled triangle because the best triangle has one angle of 90° and the other two angles are acute. Therefore, a right-angle triangle can not be one obtuse triangle and vice versa. Centroid and incenter lie within the obtuse-angled triangle when circumcenter and orthocenter lie exterior the triangle.

The triangle listed below has one angle greater than 90°. Therefore, that is called an obtuse-angled triangle or merely an obtuse triangle.


Obtuse Angled Triangle Formula

There are different formulas to calculate the perimeter and also the area of one obtuse triangle. Let's discover each that the recipe in detail.

Obtuse Triangle Perimeter

The perimeter of an obtuse triangle is the sum of the measures of all its sides. Hence, the formula because that the perimeter of an obtuse-angled triangle is:

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

Area the Obtuse Triangle

To discover the area of one obtuse triangle, a perpendicular heat is built outside the the triangle wherein the elevation is obtained. Since an obtuse triangle has actually a value of one angle more than 90°. As soon as the elevation is obtained, us can uncover the area of one obtuse triangle by applying the formula discussed below.

In the offered obtuse triangle ΔABC, we recognize that a triangle has actually three altitudes indigenous the 3 vertices to the opposite sides. The altitude or the elevation from the acute angles of one obtuse triangle lies external the triangle. We expand the base as shown and also determine the elevation of the obtuse triangle


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

Area of one Obtuse-Angled Triangle = 1/2 × base × Height

Obtuse Triangle Area by Heron's Formula

The area of an obtuse triangle can additionally be found by making use of Heron's formula. Take into consideration the triangle ΔABC through the length of the sides a, b, and c.

Heron's formula to find the area of one obtuse triangle is: \(\sqrt s(s - a)(s - b)(s - c)\), where, (a + b + c) is the perimeter of the triangle and also S is the semi-perimeter which is offered by (s): = (a + b + c)/2

Properties the Obtuse-Angled Triangles

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

Property 1: The longest next of a triangle is the side opposite come the obtuse angle. Consider the ΔABC, next BC is the longest side which is opposite come the obtuse edge ∠A. See the image below for reference.


Property 2: A triangle have the right to only have one obtuse angle. We understand that the angle of a triangle sum up to 180°. Consider the obtuse triangle shown below. We deserve to observe that among the angle measures higher than 90°, making the an obtuse angle. For instance, if one of the angles is 91°, the amount of the various other two angles will be 89°. Hence, a triangle cannot have actually two obtuse angles due to the fact that the sum of every the angles cannot exceed 180 degrees. Observe the image given below to understand the same with one illustration.


Property 3: The amount of the other two angle in one obtuse triangle is constantly smaller than 90°. We simply learned that once one the the angles is an obtuse angle, the other two angles add up to much less than 90°.


In the over triangle, ∠1 > 90°. We recognize that through angle amount property, the amount of the angles of a triangle is 180°. Therefore, ∠1 + ∠2 + ∠3 = 180° and also ∠1 > 90°

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


Circumcenter (H), the median allude from all the triangle vertices, lies exterior in an obtuse triangle. As checked out in the photo below:


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Example 2: uncover the elevation of the provided obtuse-angled triangle who area = 60 in2 and base = 8 in.



Area of an obtuse-angled triangle = 1/2 × base × height. Therefore, the height of the obtuse triangle deserve to be calculated by:

Height = (2 × Area)/base

Substituting the values, we get:

Height = (2 × 60)/8 = 15 inches

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

Example 3: have the right to sides measuring 3 inches, 4 inches, and 6 inches form an obtuse triangle?


The sides of an obtuse triangle should satisfy the problem that the amount of the squares of any two sides is lesser than the square of the third side.

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We understand that

a = 3 in

b = 4 in

c = 6 in

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

We recognize that, a2 + b2 2

36 > (9 + 16)

The offered measures can form the political parties of one obtuse triangle. Therefore, 3 inches, 4 inches, and 6 inches deserve to be the sides of one obtuse triangle.