In the diagram at right, $∠DCA$ is referred to as an exterior angle of $ΔABC$ because it lies outside the triangle and is formed by extending a side of the triangle.  

1. If $m∠CAB=46°$ and $m∠ABC=37°$, what is $m∠DCA$? Show all work. 

   Hint (a):

   How do the angles of a triangle relate to each other? How will this help you solve for $∠DCA$?

   Step 1:

   $46°+37°+∠ACB=180°$ Then how are $∠ACB$ and $∠ACD$ related?

2. If $m∠DCA=135°$ and $m∠ABC=43°$, then what is $m∠CAB$? 

   Hint (b):

   Use similar methods to those used for part (a). The methods might be used in a different order.