Things you can comfortably assume

**1. Any line or line segment that is drawn to look straight is straight.** This means there is no hidden bend or curve to the figure. It it looks straight, rest assured that it is straight! Be careful, though: this doesn't mean a given line or segment is horizontal, collinear, or anything beyond "straight."

**2. If a given figure is named (e.g. Figure A is a polygon) you can assume the figure has all the properties of that type of shape.** This means it’s important to know the theorems and the defined properties of shapes. You should know what it means if something is an equilateral triangle or a rhombus, so brush up on your geometry rules!

Things you should never assume

**1. A figure is never drawn to scale.** If you are not told specifics about lengths, angles, etc. then you cannot make any assumptions about them, no matter how convincing a figure is. Even if a figure looks like a square, if it isn't *called* as square, you can't say it is one. You need to know about its sides, angles, whether the sides are parallel, etc. Many fall into this trap, so don't be among them!

**2. Don't eyeball any measurements for lengths or angles, either.** You cannot assume right angles, for example, unless the diagram is marked with the perpendicular square symbol in the corner or you are told that the figure is a specific shape that has right angles. Likewise, lengths may not be the same and lines may not be parallel, even if they look that way at a glance.

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