special right triangles. 45-45-90 right isosceles triangle leg hypotenuse legs are congruent...
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Special Right Special Right TrianglesTriangles
45-45-9045-45-90Right Isosceles TriangleRight Isosceles Triangle
Leg
Leg
Hyp
oten
us
e Legs are congruent
Hypotenuse =
Legs =
2Leg
2
Hypotenuse
2
2Hyp
2
2
45-45-9045-45-90Right Isosceles TriangleRight Isosceles Triangle
s
s
21
23
21 2124221 26
262
212
2
12
26
64 64
383243224124264
38
LegLeg LegLeg HypHyp
11 11
3333
22
1212
2s
45-45-9045-45-90Right Isosceles TriangleRight Isosceles Triangle
Leg
Leg
1-If the perimeter of the square is 28, what is the length of the diagonal?
2- If the diagonal has a length of 12, what is the perimeter of the square?
Area?
The diagonal of a square is the Hypotenuse of two isosceles right triangles.
1- Perimeter = 28 4x = 28 x = 7 Leg = 7 Hyp = 7 2
2- Diagonal = 12
Leg = 12÷ 2 = 6 2
P = 4(6 2) =24 2
A = 6 2·6 2 = 72
30-60-9030-60-90
LongLeg
ShortLeg
Hyp
oten
us
eKnow the Short Leg (SL):
Hypotenuse = 2 · SL Long Leg =
Know Hypotenuse:
Short leg = ½ Hypotenuse
Know Long Leg (LL): Short leg =
3
3LL
3
LL
30°
60°
3 SL
30-60-9030-60-90
3x
x
2x
ShortShortLegLeg
Long Long LegLeg
HypHyp
32
36
312
11 2233 66
4422
121266
1212 2424
1212
3
33
34 38
3
12
3
3
3
12
3
312
9
312 34
30-60-9030-60-90When you draw the altitude of an equilateral triangle, you create two 30-60-90 triangles.
The triangle side length is the hypotenuse of the 30-60-90.
Half of the side length is the short leg of the 30-60-90.
The altitude, then, is half the triangle side times the square root of 3.
60°
60°
60°
30°
x
2x
3x
2x
30°