slope triangle 48 videos

Area of Triangles
Geometry Area
How to derive the area of a triangle formula using the rectangle area formula.
area triangles rectangles altitude 
Types of Triangles
Geometry Geometry Building Blocks
How to classify a triangle based on its side lengths and angle measures.
equiangular equilateral isosceles right acute obtuse triangles 
Triangle Angle Sum
Geometry Triangles
How to apply the triangle angle sum theorem.
triangle angle sum theorem 180 degrees 
Similar Triangles in Circles and Right Triangles
Geometry Similarity
How to determine if two triangles in a circle are similar and how to prove that three similar triangles exist in a right triangle with an altitude.
similar inscribed angles intercepted arc right angle circle 
Using Sine to Calculate the Area of a Triangle
Geometry Basic Trigonometry
How to calculate the area of any triangle using two sides and an included angle.
area of a triangle sine 
Special Isosceles Triangle Properties
Geometry Triangles
How to identify a segment from the vertex angle in an isosceles triangle to the opposite side.
isosceles triangle angle bisector altitude median 
Triangle Midsegment Properties
Geometry Polygons
How to define a triangle midsegment and describe its special properties.
midsegment triangle parallel bases midpoint third side 
Corresponding Parts of Similar Triangles
Geometry Similarity
How to relate corresponding altitudes, medians and angle bisectors in similar triangles.
similar triangles altitude median angle bisector proportional 
306090 Triangles
Geometry Pythagorean Theorem
How to find the legs and hypotenuse in 306090 triangles when given: the short leg, the long leg, or the hypotenuse.
right triangle short leg long leg hypotenuse 
Constructing a Triangle Midsegment
Geometry Constructions
How to define a midsegment in a triangle.
midpoint segment median 
454590 Triangles
Geometry Pythagorean Theorem
How to find the length of a leg or hypotenuse in a 454590 triangle using the Pythagorean Theorem.
isosceles right triangle leg hypotenuse Pythagorean theorem square root 
Isosceles Triangles
Geometry Triangles
How to define isosceles triangles, their components and how to determine their properties.
vertex angle leg base base angle converse remote interior angles 
Triangle Side Inequalities
Geometry Triangles
How to determine the triangle side inequalities.
shortest distance side length inequalities 
Triangle Side and Angle Inequalities
Geometry Triangles
How to determine the relationship between the side inequalities and angle inequalities in a triangle.
angles smallest to largest sides smallest to largest 
HL
Geometry Triangles
How to use the hypotenuse leg shortcut to determine the congruence of right triangles.
hypotenuse leg triangle congruence right triangles 
Proportional Segments Between Parallel Lines
Geometry Similarity
How to prove two triangles are similar using a line parallel to a base.
parallel lines triangles similar triangles proportion 
Indirect Measurement
Geometry Similarity
How to use similar triangles to measure the height of objects.
indirect measurement similar triangles measurement 
Converse of the Pythagorean Theorem
Geometry Pythagorean Theorem
How to use the converse of the Pythagorean Theorem to determine if a triangle is a right triangle, how to use Pythagorean triples to memorize the lengths of certain right triangles.
right triangle leg hypotenuse converse Pythagorean triples 
Similarity Shortcuts
Geometry Similarity
How to determine if two triangles are similar using a shortcut.
similar triangles AA SAS SSS proportion congruence 
CPCTC
Geometry Triangles
How to use the principle that corresponding parts of congruent triangles are congruent, or CPCTC.
corresponding parts or congruent triangles proofs