The number of degrees in 1 rotation of a circle = 360o. You have accounted for 243.5 degrees. What is left over is the answer.
<EAD and <ECD
Both of these are tangents to a circle. Tangents meet radii at 90 degree angles.
<EAD = <ECD = 90 degrees
<ABC
<ABC is 1/2 the central angle. The Central angle is <AEC
< AEC = 116.5
<ABC = 1/2 * 116.5
<ABC = 58.25
<ADC
There are 2 ways of doing this. You should know both of them.
<em><u>One</u></em>
All quadrilaterals = 360 degrees. You know three of the angles. You should be able to find ADC
<ADC + 90 + 90 + 116.5 = 360 Add the four angles together.
<ADC + 296.5 = 360 Combine terms on the left
<ADC = 360 - 296.5 Subtract 238.25 from both sides
<ADC = 63.5 Answer
<em><u>Method Two</u></em>
<ADC = 1/2 (major Arc - Minor Arc) This formula is fundamental to circle / tangent properties. The Major arc is the larger of the two parts of the circumference of a circle. The Minor arc is the smaller.
