Problem 688: Triangle, Angles, 10, 20, 30, 40, 60 Degrees, Measure,

The drawing shows a triangle ABC with points E and D on AB and AC, respectively. If the measure of the angles BAC, ACE, BCE, and ABD are 20, 30, 10, and 60 degrees, respectively, find the measure of angle BDE.

Triangle, Angles 10, 20, 30, 40, 60 degrees, Measure

How to Solve It, Interactive Mind Map

George Pólya's 1945 book "How to Solve It, A new aspect of Mathematical Method", is a book describing methods of problem solving. It suggests the following steps when solving a mathematical problem: (1) First, you have to understand the problem. (2) After understanding, then make a plan. (3) Carry out the plan. (4) Look back on your work. How could it be better? 

Mind Map Help. To see a note: Hover over a yellow note button. To Fold/Unfold: click a branch. To Pan: click and drag the map canvas.

College Geometry: Gergonne Point, Online Education

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