Video narration
Are these measurements enough to draw the roof exactly? On your house drawing, the base DE is five centimetres long. Mark BD and CE, the two side walls, at five centimetres each. Use your ruler on the page to mark each length carefully, keeping each label with its matching side. That records exactly what the measurements do tell you. Now the door: one centimetre wide and two centimetres high. Its size is given, but not its position, so don't treat any spot as specified. That tells you about the door, not the roof. But the measurements do not define the roof. Without a shape or angle, there is no exact roof line for your ruler to follow. To construct it accurately, you need the roof's shape or angle, or instructions for drawing it. Not yet. Your house drawing needs that missing roof information before you can finish accurately.