Question

can someone please help me with this I don't understand it and if possible could you write out the formula for me so I can get a better understanding.

Answer 1

m∡DCE = 100º

1) Since ∡DCG = ∡DCE + ∡ECF +∡FCG, by the angle addition postulate we can write:

∡DCG = ∡DCE + ∡ECF +∡FCG

145º = ∡DCE +20º +25º Let's solve for ∡DCE

145º -45º =∡DCE

∡DCE = 100º

2) So the m∡DCE = 100º