Complementary angles are angles that sum up to 90°
We know that:
1- MLC=KJC.
2- KLM=90.
KLM is composed of KLC and MLC.
This means that:
KLC+MLC=90°
Since MLC=KJC, we can write this as KLC+KJC=90°.
This is the definition of complementary (two angles whose sum is 90 degrees).
