Find Alpha in an 80° Triangle: Geometric Angle Measurement

Question

Find the measure of the angle $\alpha$

00:00 Find the value of A

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

00:06 We'll substitute appropriate values according to the given data and solve for A

00:11 Group the terms

00:14 Isolate A

00:19 And this is the solution to the question

Let's remember that the sum of angles in a triangle is equal to 180 degrees.

Therefore, we will use the following formula:

$A+B+C=180$

Now let's input the known data:

$80+55+\alpha=180$

$135+\alpha=180$

We'll move the term to the other side and keep the appropriate sign:

$\alpha=180-135$

$\alpha=45$