Geometry True, Sometimes True, False

Sometimes

If a triangle is obtuse, it is isosceles

Always

If all angles of a quadrilateral are right angles then it is a parallelogram

Always

If each pair of consecutive angles of a quadrilateral are supplementary then it is a parallelogram

Always

If one of the angles of an isosceles triangle is 60 degrees the triangle is equilateral

Always

If one of the diagonals of a quadrilateral is the perpendicular bisector of the other, the quadrilateral is a kite.

Sometimes

If one pair of opposites sides of a quadrilateral are congruent and one pair of opposite sides are parallel then it is a parallelogram.

Sometimes

If the diagonals of a quadrilateral are congruent then it is a parallelogram

Sometimes

If the diagonals of a quadrilateral are congruent, the quadrilateral is an isosceles trapezoid

Always

If the diagonals of a quadrilateral divide each angle into two 45-degree angles, the quadrilateral is a square

Never

If the midpoints of the sides of a rhombus are joined in order, the figure formed is equilateral but not equiangular

Sometimes

If the midpoints of the sides of a scalene quadrilateral are joined in order, the figure formed is equilateral

Always

If the number of the sides of an equiangular polygon is doubled the measure of each exterior angle is halved

Never

If the ratio of the measures of a pair of corresponding sides of two polygons is 3:4 the the ratios of the polygons perimeters is 5:6.

Never

If the sides of one triangle are doubled to form another triangle each angle of the second triangle is twice as large as the corresponding angle of the first triangle

Sometimes

If two of the angles of a trapezoid are congruent, the trapezoid is isosceles.

Always

If two sides of a right triangle are congruent to the corresponding parts of another right triangle, the triangles are congruent.

Sometimes

If two sides of one triangle are proportional to two sides of another triangle the triangles are similar

Always

If two triangles are congruent then they are similar

Sometimes

If two triangles are similar then they are congruent

Never

One of the base angles of an isosceles triangle has a measure greater than that of one of the exterior angles of the triangle.

Sometimes

Planes that contain two skew lines are parallel

Sometimes

Supplements of complementary angles are congruent

Sometimes

A kite is a parallelogram

Never

A median of a triangle does not contain the midpoint of the side to which it is drawn

Never

A parallelogram has three diagonals

Always

A polygon has the same number of sides as vertices

Always

A rectangle is a polygon

Always

A regular polygon is equilateral

Sometimes

A rhombus is square

Never

A right triangle is congruent to an obtuse triangle

Always

A square is a rhombus

Never

A trapezoid has three bases

Never

A triangle contains two obtuse angles

Sometimes

If a parallelogram is equilateral. It is equiangular.

False

True or False? A line that is perpendicular to a horizontal line is vertical

True

True or False? A triangle is a plane figure

False

True or False? Every four sided figure is a plane figure

True

True or False? If a line and a plane never meet, they are parallel.

False

True or False? If a line is perpendicular to a line in a plane it is perpendicular to the plane

False

True or False? If a line is perpendicular to a plane, it is perpendicular to every line in the plane

True

True or False? If a line is perpendicular to two planes, the planes are parallel.

True

True or False? If a plane and a line not in the plane are each perpendicular to the same line, then they are parallel to each other.

False

True or False? If a plane contains one of two skew lines, it contains the other.

False

True or False? If two parallel lines lie in different planes, the planes are parallel.

True

True or False? In a plane two lines perpendicular to the same line are parallel

False

True or False? In space, two lines perpendicular to the same line are parallel

False

True or False? It is possible for two planes to intersect at one point

False

True or False? Three parallel lines must be coplanar

False

True or False? Two lines must either intersect or be parallel

False

True or False? Two lines perpendicular to the same line are parallel

Sometimes

Two equilateral polygons are similar

Always

Two equilateral triangles are similar

Always

Two isosceles triangles are similar if a base of angle of one is congruent to a base angle of the other.

Always

Two isosceles triangles are similar if the vertex angle of one is congruent to the vertex angle of the other

Always

Two parallel lines determine a plane

Sometimes

Two rectangles are similar if neither is a square.

Sometimes

Two right triangles are similar

Always

Two right triangles are similar if the legs of one are proportional to the legs of the other

Sometimes

Two triangles are congruent if two side and an angle of one are congruent to the corresponding parts of the other.

Never

All three altitudes of a triangle fall outside of the triangle

Always

An equiangular triangle is isosceles

Sometimes

An equilateral polygon is regular

Never

An equilateral triangle is similar to a scalene triangle

Sometimes

An exterior angle of a triangle is larger in measure than any angle of a triangle

Never

An obtuse angle is similar to an acute triangle

Never

As the number of sides of a polygon increases the sum of the measures of the exterior angles increases

Always

As the number of sides of a polygon increases, the number of exterior angles increases

Always

If A, B, C, and D are noncoplanar, AB is perpendicular to BC and AB is perpendicular to BD the AB is perpendicular to the plane determined by B, C, and D.

Always

If a line intersects a side of a triangle at one of its trisection points and is parallel to a second side then it intersects the third side at one of its trisection points

Always

The acute angles of a right triangle are complementary

Never

The bisector of the vertex angle of a scalene triangle is perpendicular to the base.

Sometimes

The measure of an exterior angle of a decagon is greater than the measure of an exterior angle of a quadrilateral

Sometimes

The number of diagonals in a polygon is the same as the number of sides.

Sometimes

The sum of the lengths of the diagonals of a polygon is greater than the perimeter of the polygon

Always

The sum of the measures of the angles of a polygon formed by joining consecutive midpoints of a polygon's sides is equal to the sum of the measures of the angles of the original polygon

Always

The supplement of one of the angles of triangle is equal in measure to the sum of the other two angles of the triangle