The ratio of the length to the width is 12/3=4, so the actual windscreen will have the same ratio. If the width is x then the length is 4x and the area 4x²=1.21sq m. Therefore x²=1.21/4=1.1²/2² and x=1.1/2=0.55m so the length is 4×0.55=2.2m. The dimensions of the windscreen are 2.2 by 0.55 metres.