AMO 2021 – Primary 6 (Grade 6) Question 12

Question 12

Points $C,D,E,F$ lie on a circle with center $A$ on $CE$. Given $CE=2$ cm, $CD=DE$ and $\angle ECF=30^\circ$, find the perimeter of $CDEF$ in centimeters.

Question illustration

$\sqrt5-\sqrt2+2$
$\sqrt3+2\sqrt2+1$
$2\sqrt3+\sqrt2-1$
$\sqrt6-2\sqrt2+5$
$\sqrt3+4\sqrt2-1$