• #### Cyclic Quadrilaterals and Parallel Lines in Circles - Concept

##### Math›Geometry›Circles
How to prove that opposite angles in a cyclic quadrilateral are congruent; how to prove that parallel lines create congruent arcs in a circle.
• #### Radii to Tangents - Concept

##### Math›Geometry›Circles
How to define a tangent line; how to determine the angle a radius to a tangent forms.
• #### Rotations - Problem 3

##### Math›Geometry›Transformations
How to find the angle of rotation in an isometry where the point of rotation is not given.
• #### Using a Protractor - Concept

##### Math›Geometry›Geometry Building Blocks
How to use a protractor to measure an angle.
• #### Rhombus Properties - Problem 2

##### Math›Geometry›Polygons
How to find the length of diagonals and angles in a rhombus.
• #### Radii to Tangents - Problem 1

##### Math›Geometry›Circles
How to calculate the central angle formed by radii to tangents that intersect at a point outside the circle.
• #### Rhombus Properties - Problem 1

##### Math›Geometry›Polygons
How to find the angles in a rhombus created by drawing one diagonal.
• #### Special Isosceles Triangle Properties - Concept

##### Math›Geometry›Triangles
How to identify a segment from the vertex angle in an isosceles triangle to the opposite side.
• #### Constructing Parallel Lines - Problem 1

##### Math›Geometry›Constructions
How to construct parallel lines using corresponding angles.
• #### Corresponding Parts of Similar Triangles - Problem 1

##### Math›Geometry›Similarity
How to find the length of an angle bisector using similar triangles.
• #### Constructing Parallel Lines - Problem 2

##### Math›Geometry›Constructions
How to construct parallel lines using alternate interior angles.
• #### Properties of Similar Polygons - Problem 1

##### Math›Geometry›Similarity
How to identify if two quadrilaterals are similar, given three angles and four sides.
• #### The Definitions of Sine and Cosine - Problem 2

##### Math›Trigonometry›Trigonometric Functions
How to find the sine of an angle when its cosine is given.
• #### Corresponding Parts of Similar Triangles - Concept

##### Math›Geometry›Similarity
How to relate corresponding altitudes, medians and angle bisectors in similar triangles.
• #### Rectangle and Square Properties - Problem 1

##### Math›Geometry›Polygons
How to find the angles in a square created by drawing diagonals, and finding the lengths of those diagonals.
• #### The Definitions of Sine and Cosine - Problem 2

##### Math›Precalculus›Trigonometric Functions
How to find the sine of an angle when its cosine is given.