Special Right Triangles
Draw 5 squares with each side length increasing by
Find the length of each diagonal
1 a 2 + b 2 = c = c = c 2 2 = c 2 2 = c
Find the length of each diagonal 1 2 a 2 + b 2 = c = c = c 2 8 = c 2 8 = c 2 2 = c
Find the length of each diagonal a 2 + b 2 = c = c = c 2 18 = c 2 18 = c 3 2 = c
Find the length of each diagonal a 2 + b 2 = c = c = c 2 32 = c 2 32 = c 4 2 = c
Find the length of each diagonal a 2 + b 2 = c = c = c 2 50 = c 2 50 = c 5 2 = c
Do you see the pattern 2 4 2 3 2 2 2 2 Side length time square root of 2
Now, what do you know about squares and the triangle formed by the diagonal. A square has 4 equal sides and 90° angles The triangle is isosceles right
If the triangle is isosceles right, then what do you know about the base angles? 45°
An isosceles right triangle is a triangle 45°
triangles follow the same pattern we found in the squares. 45° a a 2 So if you know one side you can find the other.
Find the missing sides 45° 8 8 2 c 8
Find the missing sides 45° a 7 2 7 7
Find the missing sides 2 c 25
Find the missing sides a 16 2 16
triangles will have two basic diagrams that you will need to recognize. 45°
You will have to know triangles… the hypotenuse = leg 2 45°
OR.. the leg = hypotenuse 2 45°
There is a second “special right triangle”… Obviously if one angle is 30° then the other is 60° 30° Angle Sum of Triangle
triangle The short leg (a) is always opposite the 30° angle 30° a
triangle The hypotenuse is always 2 times short leg 30° 2a a
Draw five triangles Each short leg increasing by 1 30° ° Find the long leg b b b b b
a 2 + b 2 = c b 2 = b 2 = 4 b 2 = 4-1 b 2 = 3 b = 3 30° 2 1 b
Find the long leg a 2 + b 2 = c b 2 = b 2 = 16 b 2 = 16-4 b 2 = 12 b = 12 b = 2 3 30° b b
Find the long leg a 2 + b 2 = c b 2 = b 2 = 36 b 2 = 36-9 b 2 = 27 b = 27 b = 3 3 30° b b 6 3 b
Find the long leg a 2 + b 2 = c b 2 = b 2 = 64 b 2 = b 2 = 48 b = 48 b = 4 3 30° b b 6 3 b 8 4 b
Find the long leg 30° b b 6 3 b 8 4 b 10 5 b a 2 + b 2 = c b 2 = b 2 = 100 b 2 = b = 75 b = 5 3
Do you see the pattern? 30° 3 30° 4 4 3 30° 5 5 3 2 3 3 Long leg = short leg time the square root of 3
triangle 30° 2a a a3a3
Find the missing side 30° h 8 8383 16 b