ABC is a right triangle.
If
Calculate the size of .
We have hundreds of course questions with personalized recommendations + Account 100% premium
ABC is a right triangle.
If
Calculate the size of .
Let's begin by observing the triangle ABC, where we are given two angles.
Due to the fact that the sum of angles in a triangle equals 180 we are able to calculate angle C in the following way:
Now let's proceed to observe triangle CMD, where we are given two angles.
Given that the sum of angles in a triangle equals 180, we are able to calculate angle CDM in the following way:
50
Indicates which angle is greater
Because angle C in triangle ABC becomes an interior angle in triangle CDM! You need this 40° angle to apply the triangle sum rule in the second triangle.
Always start with the triangle where you have the most known angles. Here, triangle ABC has angles of 90° and 50°, so solve it first to find the missing 40°.
Focus on one triangle at a time. List the three angles in each triangle separately, then apply the 180° rule. Don't try to solve both triangles simultaneously!
This happens because both triangles share the same angle relationships! Triangle CDM has a 90° angle and the 40° angle from point C, leaving for angle CDM.
No! You need all three angles in triangle ABC to understand the geometry. Skipping angle C means you won't know what angle to use in triangle CDM.
Get unlimited access to all 18 Angles questions, detailed video solutions, and personalized progress tracking.
Unlimited Video Solutions
Step-by-step explanations for every problem
Progress Analytics
Track your mastery across all topics
Ad-Free Learning
Focus on math without distractions
No credit card required • Cancel anytime