```Straight Angle = 180&deg; Angles , Perimeter and Area Reference Sheet Types of Angles Right Angle Acute Angle Obtuse Angle = 90&deg; Greater than π&deg; Greater than 90&deg; Less than 90&deg; Less than 180&deg; Adjacent Angles b a c Two angles that share a common side and vertex a and b are adjacent a and c are NOT adjacent Angle Relationships Complementary Supplementary Angles Angles 53&deg; 37&deg; 102&deg; 78&deg; Two adjacent Two adjacent angles. The sum of angles. The sum of their their measurements measurements equal 90&deg; equal 180&deg; Vertical Angles 94&deg; a 86&deg; b When two lines cross, the angles opposite of each other are vertical angles, they share a common vertex and the same measurement. a and 86&deg; are vertical angles b and 94&deg; are vertical angles Perimeter and Area Perimeter is the distance around a 2-&shy;βdimensional closed geometric shape. Area is the amount of surface it covers. Square Rectangle Parallelogram s w h w s Equations: s = side Perimeter = 4s Area = ππ l b Equations: Perimeter = 2l + 2w Area = lw Equations Perimeter = 2w + 2b Area = bh Triangle h h b Equations: Perimeter = add all sides π