Geometry Problem 1146: Triangle, Interior Point, 10, 20, 30, 130 degrees, Congruence. Level: School, College, Mathematics Education

A point D is inside a triangle ABC (figure below) such that angle ACD = angle BCD = angle CAD = 10 degrees, and angle BAD = 20 degrees. Find the measure of angle CBD.
This entry contributed by Ajit Athle.


 

See also:
Triangles
Angles
Angle Bisector
Congruence
Solution
Kaleidoscope of Problem 1146 base on Poincare Disk Model.
Kaleidoscope of Geometry Problem 1146, iPad Productivity Apps; Adobe Spark Post
Puzzle of problem 1146 (35 quadrilateral pieces)