Question

If m∠A = m∠B and m∠A + m∠C = m∠D, then
m∠B + m∠C = m∠D.

Answer 1

True. The statement is also equivalent to: If m<B + m<C does not equal m<D, then m<A does not equal m<B and m<A + m<C is not equal to m<D.