In isosceles triangle $ABC$, angle $BAC$ and angle $BCA$ measure 35 degrees. What is the measure of angle $CDA$?

codehtml127 Jun 29, 2018

#1**+1 **

In triangle ABC since angles BAC and BCA = 35°

Then angle ABC = 180 - 35 - 35 = 180 -70 =110°

And because ABC is an inscribed angle....then the major arc it intercepts, ADC, has twice its measure = 220°

So minor arc ABC = 360 - 220 = 140°

And since CDA is an inscribed angle intercepting this arc, it has 1/2 of its measure =

(1/2) 140 = 70°

CPhill Jun 29, 2018