if given that |a|=|b|=|a-b| find the angle between the vectors

Answer 1

the two vectors are the same length, call it 1

Draw coordinate system with a from origin to x = 1 along x axis

Now draw b, length = 1, from origin to lower right in quadrant 4

Now complete parallelogram to find a+b and a-b vectors

see that for a-b to be length of 1, need equilateral triangle so angle is 60 degrees