In an isosceles triangle ABC (AB = BC), E is on AB and D is on BC. If angle B = 20 degrees, angle DAC = 60 degrees, and angle ACE = 50 degrees, find the measure of angle ADE. Click the next (play) button below to start. See also: HTML5 version
The famous Langley problem is a type of problem called "Adventitious Angles" problem because it is a matter of chance that we will be able to solve this problem (drawing auxiliary lines). It appears to be an easy problem, but it is deceivingly difficult.
40 Quadrilateral Pieces.
Over 1200 Visually Stimulating Geometry Problems.