How to find the diameter with area sector

If the central angle measures 60 degrees, divide the 360 total degrees in the circle by 60. Multiply this by the measure of the corresponding arc to find the total circumference of the circle. Use the circumference to find the radius, then use the radius to find the area.

If the central angle measures 60 degrees, divide the 360 total degrees in the circle by 60. Multiply this by the measure of the corresponding arc to find the total circumference of the circle. Use the circumference to find the radius, then use the radius to find the area.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.