Given that mCD=20°, find mBC

Answer:
70°
Step-by-step explanation:
[tex] m\widehat {BC} = 90\degree - m\widehat {CD} [/tex]
[tex] m\widehat {BC} = 90\degree -20\degree [/tex]
[tex] m\widehat {BC} = 70\degree [/tex]