TSI MATHEMATICS CRC & DIAGNOSTIC TEST
20 KEY CONCEPTS AND REVIEW NOTES 2026
◉ Line. Answer: -A line has one dimension
-Named using any two point on a line w a two sided arrow above
them
-It can also be named using a lower-case cursive letter
◉ Collinear Points. Answer: Points that are on the same line
◉ Plane. Answer: -A plane has two dimensions
-It is represented by a shape that looks like a floor or a wall, but it
extends w/o an end
-Through any three points not on the same line there is exactly one
plane
-A plane is written using 3 non-collinear points or with upper-case
cursive letter
◉ Coplanar points. Answer: Points that lie in the same plane
◉ Line Segment. Answer: A line segment is named using both end
points with a line above them
,◉ Ray. Answer: A ray is named using its endpoint first and then any
other point on the ray pointing to the right above them
◉ Intersecting lines. Answer: 2 lines that share exactly one point
◉ Parallel lines. Answer: 2 lines that are always the same distance
apart and never touch
◉ Perpendicular lines. Answer: The relationship between 2 lines
which meet at a right angle (90degrees). Perpendicular lines= 2 lines
intersect at a right angle
◉ Right angle. Answer: 90 degrees
◉ Straight angle. Answer: 180 degrees
◉ Acute angle. Answer: between 0 degrees and 90 degrees
◉ Obtuse angle. Answer: between 90 degrees and 180 degrees
◉ Complementary angles. Answer: 2 angles that have the sum of 90
degrees
, ◉ Supplementary angles. Answer: 2 angles that have the sum of 180
degrees
◉ the sum of the angle measures in a triangle. Answer: 180 degrees
◉ Acute triangle. Answer: All angles are acute
◉ Right triangle. Answer: One angle is right
◉ Obtuse triangle. Answer: One angle is obtuse
◉ Scalene triangle. Answer: All sides have different lengths
◉ Isosceles triangle. Answer: At least 2 sides have the same length
◉ Equilateral triangle. Answer: All sides have the same length
◉ The sum of the lengths of a triangle. Answer: The sum of the
lengths of any two sides of a triangle must be greater than the length
of the third side
20 KEY CONCEPTS AND REVIEW NOTES 2026
◉ Line. Answer: -A line has one dimension
-Named using any two point on a line w a two sided arrow above
them
-It can also be named using a lower-case cursive letter
◉ Collinear Points. Answer: Points that are on the same line
◉ Plane. Answer: -A plane has two dimensions
-It is represented by a shape that looks like a floor or a wall, but it
extends w/o an end
-Through any three points not on the same line there is exactly one
plane
-A plane is written using 3 non-collinear points or with upper-case
cursive letter
◉ Coplanar points. Answer: Points that lie in the same plane
◉ Line Segment. Answer: A line segment is named using both end
points with a line above them
,◉ Ray. Answer: A ray is named using its endpoint first and then any
other point on the ray pointing to the right above them
◉ Intersecting lines. Answer: 2 lines that share exactly one point
◉ Parallel lines. Answer: 2 lines that are always the same distance
apart and never touch
◉ Perpendicular lines. Answer: The relationship between 2 lines
which meet at a right angle (90degrees). Perpendicular lines= 2 lines
intersect at a right angle
◉ Right angle. Answer: 90 degrees
◉ Straight angle. Answer: 180 degrees
◉ Acute angle. Answer: between 0 degrees and 90 degrees
◉ Obtuse angle. Answer: between 90 degrees and 180 degrees
◉ Complementary angles. Answer: 2 angles that have the sum of 90
degrees
, ◉ Supplementary angles. Answer: 2 angles that have the sum of 180
degrees
◉ the sum of the angle measures in a triangle. Answer: 180 degrees
◉ Acute triangle. Answer: All angles are acute
◉ Right triangle. Answer: One angle is right
◉ Obtuse triangle. Answer: One angle is obtuse
◉ Scalene triangle. Answer: All sides have different lengths
◉ Isosceles triangle. Answer: At least 2 sides have the same length
◉ Equilateral triangle. Answer: All sides have the same length
◉ The sum of the lengths of a triangle. Answer: The sum of the
lengths of any two sides of a triangle must be greater than the length
of the third side
