A. equilateral triangle (all 60 ${}^{\circ }$ angles) B. isosceles triangle (30 ${}^{\circ }$, 30 ${}^{\circ }$, 120 ${}^{\circ }$) C. right-angled triangle (30 ${}^{\circ }$, 60 ${}^{\circ }$, 90 ${}^{\circ }$) D. isosceles triangle (angles can be worked out using trig.) E. scalene triangle (one 60 ${}^{\circ }$ angle)