Special Right Triangles SWBAT find unknown lengths in 45°, 45°, 90° and 30°, 60°, 90° triangles

Isosceles Right Triangles  What do you know about isosceles triangles? Two sides are congruent (equal) Two angles are congruent (equal)  Right isosceles triangles Have one right angle (90°) Have two 45° angles

Special Right Triangles  There is a special relationship between the sides of a 45°-45°-90° triangle The length of the hypotenuse is √2 times the leg a a a√2 45°

Key Concept  To calculate the hypotenuse Multiply √2 by the leg  To calculate the leg Multiply √2/2 by the hypotenuse It’s considered improper form to have a radical (√) on the bottom of a fraction

Examples a 13yds 45° 12ft c 45° 25in c 45° a 39dm 45°

Classwork  Worksheet 1-6, 13, 18  Homework WB pg 57, 2-20 even

30°, 60°, 90° triangles  To calculate the leg opposite the 30° angle (the shorter leg) divide the hypotenuse by 2 C ÷ 2  To calculate the 60° angle (the longer leg) multiply the hypotenuse by √3/2 √3/2(c)

30°, 60°, 90° triangles  To calculate the hypotenuse multiply the shorter leg by 2 2a

Examples 7cm b a 30° 60° c b 4m 30° 60° 10cm b a 30° 60° c b 30yd 30° 60°

Classwork  Worksheet 7-12,  Homework WB pg58, 23-33