How to draw exactly 1/3 circle in Photoshop?

Question

I need to do a pie chart with exact 1/3 chunks. Obviously it's easy to do a quarter circle - just cut the circle in half and then cut that half in half. But how would I do 1/3 circle?

Answer 1

1. Create an origin with guides, turn on snapping.
2. Choose the polygon tool, draw a 3 sided shape (i.e. equilateral triangle) centred at the origin
3. Choose the ellipse tool, draw a circle also centred at the origin with a radius intersecting the triangle.

Answer 2

360/3=120 so you need bisect the circle with lines that are 120° perpendicular to each other.

I wouold personally do this in illustrator and inport the final image as a smart object into photoshop this will give you more editing ability with the circle latter if needed.

1. Draw the circle in illustrator
2. Draw a line from the center point to the top or bottom, use shift to keep constrained angle
3. keep line selected and cntr+c then cntr+f this copies and places new line on top of existing one.
4. rotate this new line 120°
5. copy paste and press O(mirror tool) then hold shift and flip on y-axis
6. you may have to use the direct select tool (black triangle) and have smart guides to align the anchor of the lines to the center of circle.
7. Use pathfinder pallet and click divide should be the bottom row all the way to the left. the lines disappear and you have your circle divided into thirds. delete the one you don't want and rotate to the desired angle.
8. then just copy and paste into photoshop and make sure smart object is selected.