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.
1 solution
We will use properties of cyclic quadrilaterals. First we notice that quadrilateral ABCD is cyclic and thus angle ADE = b. And now we write
a
+
b
=
1
8
0
°
−
c
=
1
8
0
°
−
4
5
°
=
1
3
5
°
(we know that angle c is 45° because the lenght of red segment is
4
1
of the perimeter of the circle.)