8. Geometry Flashcards
What is geometry?
Geometry is the branch of mathematics that deals with the properties of shapes, lines, points, angles, and other such objects and the relationships among them.
What do you know about an arc of a circle?
Arcs of a circle and sizes of angles are measured in degrees and (not very often) in minutes or even seconds; 1 degree equals 60 minutes, and 1-minute equals 60 seconds.
What does a circle have?
A circle has 360 degrees, any arc that isn’t a complete circle measures less than 360 degrees.
What is a quadrilateral?
A quadrilateral (a shape with four sides, such as a square or rectangle) has angles that add up to 360 degrees.
Two dimensional shapes can only be measured with…
length and width.
Three-dimensional shapes have…
length, width, and height (depth).
What is the perimeter of a shape?
The perimeter of a shape is the distance around it (you can view it as the shape’s boundary), and its area is all the flat space within that boundary.
How can you calculate the perimeter of 2D objects?
The perimeter of 2D objects is always the sum of the length of all its sides (even a circle has a side, though just one), and its area is usually the object’s length times its width or something pretty similar.
How does an angle can be formed?
Angles are formed when two lines intersect (cross) at a point. You typically measure angles in degrees. The greater the number of degrees the wider the angle is.
How many degrees are within a straight line?
180 degrees
How many degrees are within a right angle?
exactly 90 degrees
How many degrees are within an acute angle?
An acute angle is more than 0 degrees but less than 90 degrees.
How many degrees are within an obtuse angle?
An obtuse angle is more than 90 degrees but less than 180 degrees.
How much does a reflex angle measure?
A reflex angle measures more than 180 degrees.
What are complementary angles?
Complementary angles are two angles that equal 90 degrees when added together.
What are supplementary angles?
Supplementary angles are two angles that equal 180 degrees when added together!
What are the 7 basic different types of angles?
- Straight lines
- Right angles
- Acute angles
- Obtuse angles
- Complementary angles
- Supplementary angles
- Reflexive angles
What are vertical angles?
Vertical angles oppose each other when two lines cross. They’re always equal. Angles 4 and 2 are equal, and angle 1 and 3 are equal. In this case, the term vertical refers to where the lines cross each other; it has nothing to do with direction.
What are parallel lines?
Parallel lines never intersect. Lines are considered parallel if they’re equidistant and they’ll never meet. They also point in the same direction.
What are corresponding angles?
Corresponding angles have the same measure. They’re on the same side of the transversal and both either above or below the parallel lines.
What is the term transversal means?
Transversal means a line that crosses through a parallel line.
What are alternate exterior angles?
Alternate exterior angles are on the opposite sides of the transversal and between the parallel lines. Equality between these angles means you have a parallel line on your hands.
What are consecutive interior angles?
Consecutive interior angles are on the same side of the transversal, between the parallel lines. If these two angles add up to 180 degrees, you’re dealing with parallel lines.
How do you name angles?
You can name angles by using the vertex point and a point on each of the angle’s ray. You may see problems where angles are named ∠ABC, you can also use the vertex only to name an angle e.g., ∠B