Determine Triangle Type Using Angles X, 3X, and 5X

Question

Identify which type of triangle appears in the drawing:

00:00 What is the triangle in the drawing?

00:03 The sum of angles in a triangle equals 180

00:07 Let's use this equation and solve for X

00:13 Let's isolate X

00:17 And this is the value of X

00:21 Let's substitute this value and find the triangle's angles

00:32 Based on the angles, we can see that the triangle is obtuse

00:37 And this is the solution to the question

Let's remember that the sum of angles in a triangle equals 180 degrees.

Let's calculate X in the following way:

$3x+5x+x=180$

$9x=180$

Let's divide both sides by 9:

$x=20$

Now let's calculate the angles:

$3x=3\times20=60$

$5x=5\times20=100$

This means that in the triangle we have 3 angles: 20, 60, 100

Since we have one angle that is greater than 90 degrees, meaning an obtuse angle, this is an obtuse triangle.

Obtuse triangle