p202 q20 re.ex.9
don't know how to do [b][ii]---show that ABC is equilaqteral. thanks
I've made one observation . . . is equilateral.
. . But I haven't gone any further.
We have these areas: .
We are given the ratio of these areas: .
. . which simplifies to: .
Since is isosceles
. . then: . . . . Hence: .
Therefore: . is equilateral.