Known RT triangle ABC, angle c = 90 degrees, angle B = 30 degrees. 1, ruler drawing please God

Known RT triangle ABC, angle c = 90 degrees, angle B = 30 degrees. 1, ruler drawing please God

First draw a straight line, and then draw his vertical bisector. The intersection point is C. starting from point C, take 3cm and 4cm from the two lines respectively. The end of 3cm is point a, and the end of 4cm is point B. connect ab