whenever a line is tangent to a circle, the line segment you can draw from the center to the tangent line on the circumference is always perpendicular, so angle ACD is 90° and angle AED is 90° and we already know CAE is 98° so adding the tree would result in 278° because ACDE forms a quadrilateral it's angle have a sum of 360° so subtract 278 from 360 and you get 82°