if its an arc and center angle is given it could be double the size. IF it is a triangle measure you would use Pythagoras for triangle and trig for given angle, if two triangles are shown and they are scale of each other alternative measures given divide into each measure by the correct line and check this with the matching angles. when found as a division this is the ratio so then you just multiply to find the larger measure but divide to find the smaller measure. AC could also be a junction or vector, if its a type of vector then you just follow the arrows and count how many arrows fit the line pick a direction and ie) if its x2 a then you show a+a.
