Adjacent angles are one of the types of angles when two angles are paired. One of the benefits of understanding these angles is that it will help you solve any related questions under geometric.
All the types of angles have laws and how to use them when needed, especially when solving questions in mathematics. So, I will first discuss the meaning of adjacent angles, give some examples, and discuss how they relate to other angles.
What are Adjacent Angles?
Two angles are said to be adjacent when they share the same vertex and side. For clearer understanding, a vertex is a point where two lines or sides meet. It is important to note that adjacent angles don’t overlap.
From the diagram shown above, a and b are adjacent angles since the two angles share the same vertex (O) and side.
Adjacent angles can be supplementary angle or complementary angle. Complementary in the sense that when the two adjacent angles add up to 90 degrees and supplementary when they add up to 180 degrees.
Case 1: Supplementary
In this case, the sum of angle a and b is 180 (a + b = 180). Also, a and b are adjacent due to the same vertex and side they both have.
Case 2: Complementary
In this case, the two angles a and b are complementary because their sum is 90 degrees (a +b = 90). Also, a and b are adjacent.
From the diagram below, find angle b.
Angles 130 and b are adjacent because they have the same vertex and side. Also, they are supplementary.
130 + b = 180
b = 180 -130 = 50
b = 50 degrees