The triangle ABC has sides of length, a,b and c, as shown in the diagram. The point D lies on AB and CD is perpendicular to AB.
a) Show that asinB = bsinA.
b) Show that c = acosB + bcosA.
c) Given that c^2 = 4ab cosA cos B, show that a=b.
Could someone please show me how to do (c) of the question?
I've tried equating (b) squared to (c) but I end up with asinB = b sinA. How do I use this to prove a=b?