We know Angle A is 41° and the HYPOTENUSE (the longest side) is 170. We're looking for side b, which is the ADJACENT side (adjacent means next to, like it's literally a part of the angle A) The trig function that puts together ADJ and HYP is the cosine function.
cos 41 = ADJ/HYP
cos 41° = b/170
170cos 41° = b
You need a calculator to get a value for cos 41°. You could put in the entire 170cos41° into a calculator all at once.
