What is the expression in radical form? (7x3y2)2/7

The answer would be 35

The picture in the attached figurewe have thatsin  ∅=-77/85cos  ∅=36/85tan  ∅=-77/36sothe ∅ angle  must be in the fouth quadrantwe know thattan  ∅=y coordinate/x coordinatesotan  ∅=-77/36x coordinate=36y coordinate=> -77    (iv quadrant)the points is (36,-77)the answer is(36, –77)