Consider circle A in the diagram below where the m∠DCG=25∘ and mCF^=60∘ and prove that m∠EDF=55∘.
Given that m∠DCG=25∘, this angle intercepts arc DG^ which makes mDG^=_, this means that mED^=130∘ as EG^ is a diameter.
∠CED intercepts CFD^, which makes m∠CED=_.
∠ECD intercepts ED^ which makes m∠ECD=_.
∠CDF intercepts CF^ which is 60∘, making m∠CDF=30∘. Using the triangle sum theorem, m∠EDC=_, and using Angle addition postulate the m∠EDF=55∘.
