Please check my work. Thank you.

Find the dot product of the following vectors. Find the angle between the vectors.

v=3i+2j, w=-4i-5j

Dot product v x w=-12-10=-22

cos of angle = -22/sq. root of 13 x sq. root of 41=-0.9529

the angle = 17.64 degrees.

Please tell me where I made a mistake, because when I graph the vectors, the angle looks like it is about 100 degrees.

Thank you very much.