Geometry Lessons for Grade 8
Explore translations, rotations, reflections, and dilations; establish congruence or similarity; and apply the Pythagorean Theorem to distance and volume. These lessons give each idea room for an interactive diagram, worked examples, and hands-on exploration.
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Congruent Angles
Congruent angles have equal measure.
Open lesson →Angle Bisector
An angle bisector divides an angle into two equal angles.
Open lesson →Consecutive Interior Angles
Consecutive interior angles lie on the same side of the transversal between the lines.
Open lesson →Consecutive Exterior Angles
Consecutive exterior angles lie on the same side of the transversal outside the lines.
Open lesson →Midsegment
A midsegment connects the midpoints of two sides of a triangle.
Open lesson →Pythagorean Theorem
In a right triangle, a squared plus b squared equals c squared.
Open lesson →Isosceles Trapezoid
An isosceles trapezoid has equal legs and one pair of parallel sides.
Open lesson →Secant
A secant is a line that passes through a circle at two points.
Open lesson →Tangent
A tangent touches a circle at exactly one point.
Open lesson →Central Angle
A central angle has its vertex at the center of the circle.
Open lesson →Translation
A translation slides a figure without turning or resizing it.
Open lesson →Reflection
A reflection flips a figure across a line.
Open lesson →Rotation
A rotation turns a figure around a fixed point.
Open lesson →Dilation
A dilation enlarges or shrinks a figure by a scale factor.
Open lesson →Stretch
A stretch changes one direction more than another.
Open lesson →Glide Reflection
A glide reflection combines a translation with a reflection.
Open lesson →Slope
Slope measures rise over run and shows how steep a line is.
Open lesson →Point-Slope Form
Point-slope form writes a line using one point and its slope.
Open lesson →Slope-Intercept Form
Slope-intercept form writes a line as y equals mx plus b.
Open lesson →Congruence
Congruent figures have the same size and shape.
Open lesson →Similarity
Similar figures have the same shape but not necessarily the same size.
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