Equilateral triangle ABC and square BCDE are coplanar, as shown. What is the number of degrees in the measure of angle CAD?
+128460 Note that BC = AC = CD
So......in triangle ACD, angle ACD = angle ACB + angle BCD= 60° + 90° = 150°
And since AC = CD.....then the angles opposite these sides in triangle ACD are also equal
So....angle CAD = angle CDA
So....
angle CAD + angle CDA + angle ACD = 180
angle CAD + angle CAD + angle ACD = 180
2angle CAD + 150 = 180
2angle CAD = 180 - 150
2angle CAD = 30 divide both sides by 2
angle CAD = 15°
