GRE geometry
Terms
undefined, object
copy deck
-
3-4-5 triangle
- figure out what the multiple of 3-4-5 is
- 30-60-90 triangle
-
sides are in a 1:√3:2 ratio
- 45-45-90 triangle
- sides are in a ration of: 1:1:√2
- 5-12-13 triangle
-
no need for the pathagrean theorem; use multiples of 5-12-13
-
distance between points:
P(x1, y1) and Q(x2, y2)
-
use either:
- pythagorean theorem or
- special right triangles:
- difference b/t the x's is one leg and the difference b/t teh y's is the other leg
- Then use 3-4-5, 5-12-13, or pythagorean theorem
-
area of a circle
- A=π(r*r)
-
area of a parallelogram
- area of a prallelogram= bxh
-
area of a sector
- area of a sector= (n/360)(πr*r)
- area of a triangle
- A=1/2(bxh)
- bisector
-
divides angle into 2 equal angles
- chord
-
line segment with endpoints on the circle
- circumgerence
- c=2πr
- length of an arc
- =(n/360)(2πr)
-
perimeter of a rectangle
- P=2(L+W)
- similar triangles
-
have the same shape: corresponding sides and angles are proportional
a/a=b/b
- slope
- slope= Δy/Δx=rise/run
- triangle inequality theorem
-
If you know the length of 2 sides of a triangle, then the 3rd side is:
- greater than the positive difference
- and less than the sum of the other 2 sides
- greater than the positive difference
- verticle angles
-
angles across the vertex from each other are equal.
adjacent angles add up to 180
-
Volume of a rectangular solid
- V=LxWxH