MathDB
Find <EAD

Source: 1978 AHSME Problem 12

June 6, 2014
AMC

Problem Statement

In ADE\triangle ADE, ADE=140\measuredangle ADE=140^\circ, points BB and CC lie on sides ADAD and AEAE, respectively, and points A, B, C, D, EA,~B,~C,~D,~E are distinct.* If lengths AB, BC, CD,AB,~BC,~CD, and DEDE are all equal, then the measure of EAD\measuredangle EAD is
<spanclass=latexbold>(A)</span>5<spanclass=latexbold>(B)</span>6<spanclass=latexbold>(C)</span>7.5<spanclass=latexbold>(D)</span>8<spanclass=latexbold>(E)</span>10<span class='latex-bold'>(A) </span>5^\circ\qquad<span class='latex-bold'>(B) </span>6^\circ\qquad<span class='latex-bold'>(C) </span>7.5^\circ\qquad<span class='latex-bold'>(D) </span>8^\circ\qquad <span class='latex-bold'>(E) </span>10^\circ
* The specification that points A,B,C,D,EA,B,C,D,E be distinct was not included in the original statement of the problem. If B=DB=D, then C=EC=E and EAD=20\measuredangle EAD=20^\circ.