If twice ∠A is subtracted from the supplement of ∠A, then the remaining angle exceeds the complement of ∠A by 4 degrees. Find the size of ∠A.
Solution
Remember that ∠A and its supplement ∠S always sum to 180 degrees, and ∠A plus its complement ∠C make 90 degrees. Thus,
∠S∠C==180−∠A,90−∠A.
Using the information given in the problem, we know that:
∠S−2∠A=∠C+4.
Substituting and solving algebraically, we get:
(180−∠A)−2∠A180−3∠A86∠A====(90−∠A)+4,94−∠A,2∠A,42.
We have arrived at the solution.