Although it may seem obvious from the diagram of rectangle abcd pictures triangle dmc is isosceles explain why this must be true

Afitness center has 2 membership plans one has a low dollar sign up fee of 15 dollars and costs 38 dollars per month to join. a second plan has a higher sign up fee of 78 dollars but a lower monthly fee of 31 dollars for what number of days of the month is the coat the same