Geometry Flashcards
What is the area of a rectangular field that is 25 feet long, 12 feet wide?
300 ft2 (units are square feet)
A = LW (Area = Length*Width)
Multiplying by 25 –> can think of it as 12 quarters is 3 dollars (300 cents).
What is the perimeter of a rectangle with length 19 and width 13?
64
P = 2(L+W) = 2*32 =64
or, 2L+2W, but this is 3 steps to calculate instead of 2
If a rectangle has an area of 100, what is the minimum perimeter?
The minimum perimeter for rectangle of a fixed area is a square shape.
Take square root of 100 –> 10 on each side of square
4*10 = 40
What is the formula for volume of a rectangular solid? (also known as a “rectangular prism”)
V = LWH (length*width*height)
If 2 lines are perpendicular, what does that mean?
They form a right angle.
It is indicated by the square symbol below (dotted gray line)
What is the pythagorean theorem?
What is the formula for the diagonal of a rectangular solid?
This is called the Deluxe Pythagorean Theorem
(Pythagorean Theorem applied to 3 dimensions)
3
32 +42 = 52
The 3-4-5 triangle is good to memorize.
Other right triangles can have the same ratio: 6-8-10, 9-12-15, etc.
What is true about an isocoles triangle?
How do we draw it and identify the properties?
If 2 sides are equal, the 2 angles opposite those sides are equal, and vice versa
What are the angles of an isocoles right triangle?
What does it look like?
45-45-90
Right triangle means it has a 90 degree angle.
The 2 other angles are equal, so they must be 45 degrees. (angles sum to 180)
What is the area of this triangle?
6
A = 1/2 bh
(1/2 * base * height, where the base and height are perpendicular)
1/2 * 4 * 3 = 6
What is the ratio of the sides of a 45-45-90 right triangle?
If we draw a diagonal across a square, what shapes are formed?
What is the ratio of the sides of a 30-60-90 right triangle?
What is the formula for area of a circle?
πr2
(pi r squared)