SECTION 11.2 Areas of Parallelograms, Triangles, and Rhombuses

Heights of Parallelograms and Triangles The height MUST be an ALTITUDE!

PARALLELOGRAMS Area = base · height A = bh HINT: There is a special right triangle again!!!! 30 o 6

TRIANGLES Area = ½ base x height A = ½ bh Heights can be OUTSIDE the triangle!

TRIANGLES A = ½ bh Find the area of a triangle with sides 10,10, You need to find the height so ADD a line! 4 4 Use Pythagorean Theorem to find the height h 2 = h 2 = 100 h 2 = 84

TRIANGLES A = ½ bh Find the area of an equilateral triangle with sides

RHOMBUS Area = half of the product of the diagonals A = ½ d 1 d 2

RHOMBUS A = ½ d 1 d 2 Another Special Right Triangle! They are everywhere! 60 o 9 9

SAT Problem. Find the base length of a triangle with an area of 52 cm 2 and a height of 13 cm. a)2 cm b)4 cm c)8 cm d)16 cm e)26 cm 13 cm A = ½ bh 52 = ½ b(13) 52 = 6.5b 8 = b

Practice Page 431 WRITTEN EXERCISES #2-20 EVENS, draw pictures!!!!!