Consider an equilateral triangle ABC of side r. Reflect A about BC to form a point D. Let E be the midpoint of BD and F be the reflection of E about DC. Let there be a point P such that triangle ABF is congruent to triangle ACP. Consider the triangle FPA. Let I be the incentre, O be the orthocentre of FPA. Let the circumcentre of AIO be X. Draw a circle of radius r passing through X, and let Y be a point such that XY is the diameter. In the circle passing through X and Y, let M and N be points such that B is tangent to the circle at points M and N respectively. Using only elementary geometry, find angle ABD in degrees.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
useless useless useless useless useless time waste time waste time waste stop it guys