2. Congruent Triangles
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Begin by using the Triangle Angle-Sum Theorem. Then, consider the Third Angles Theorem, to write a system of two equations.
x=4
y=2
Let's add some labels to the given diagram.
Before we try to find the values of x and y, we will use the Triangle Angle-Sum Theorem to find the measure of ∠A.
m∠B= 148, m ∠C= 18
Add terms
LHS-166=RHS-166
(I): Add (II)
(I): Add and subtract terms
(I): .LHS /8.=.RHS /8.
(I): Rearrange equation
Now we can find the value of y by substituting the value of x into Equation (II).