# please find the side length of an equilateral triangle

#### Albert

##### Well-known member
P is an inner point of equilateral triangle ABC ,
given PC=3, PA=4,PB=5 ,please find the side length of the equilateral triangle

#### caffeinemachine

##### Well-known member
MHB Math Scholar
P is an inner point of equilateral triangle ABC ,
given PC=3, PA=4,PB=5 ,please find the side length of the equilateral triangle
Rotate the trianlge by 60 degrees about the point C. Let $P'$ be the new position of $P$. Then $\angle P'PA=90$. Thus we get a triangle $CPA$ with $\angle CPA=150$ and $PC=3, PA=4$. To find $AC$.

solution :

MHB Math Scholar