Question

In the diagram shown, ray CD is perpendicular to ray CE. If the measure of DCF is 115then what is the measure of ECF?

Answer 1

m∠FCE =25º

1) Since the measure of ∠DCF = 115º and ∠DCE = 90º then by the Angle Addition postulate we can state that

∠DCF = ∠DCE +∠FCE Plugging into that the given values

115º = 90º + ∠FCE Subtracting 90º from both sides

115-90=∠FCE

25º =∠FCE

2) Then the measure of ∠FCE is 25º