Answer all the questions below and press submit to see how many you got right.
Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.
Angle : If two line segments (or rays) both start at a common point the opening between the two line segments is called an angle. The common point is called vertex of the angle. The size of an angle is measured in degrees.
Center : The center of a circle is the unique point in the circle, such that all points on the boundary of the circle have a constant distance equal to the radius from that point. The center of a regular polygon is the point that has equal distance from all its corners.
Circle : A circle is a two-dimensional shape. The boundary of a circle is a set of points that has the same distance (the radius) from the center of the circle.
Corner : A corner of a shape is a point in the shape such that this point does not lie on the line segment between any two other points in the shape. Every triangle has 3 corners and every quadrilateral has 4 corners.
Counterexample : A counterexample to a statement of the form 'all objects of type x have property y' is an object of type x that does not have property y. A counterexample to a statement shows that the statement is not true in general. For example the number 3 is a counterexample to the statement that all numbers are even.
Cyclic quadrilateral : A quadrilateral is called cyclic if all of its 4 corners lie on the same circle. In a cyclic quadrilateral opposite angles are complementary.
Degree : For angles one degree is defined as the angle represented by a $\frac{1}{360}$ of the angle represented by a full circle. For measuring temperatures one can use either degrees Celsius or degrees Fahrenheit. In a polynomial the degree describes the highest exponent of $x$ that has a non-zero coefficient. For example the degree of $1+x+x^2$ is 2.
Diagonal : A diagonal in a quadrilateral is the line segment between a corner and its opposing corner. A diagonal in a cube (or rectangular prism) is the line segment between two corners that are not part of a same face.
Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.
Line : A line AB is a one-dimensional shape that includes the points A and B, all the points on the line segment in between A and B and all the points of the straight extension of the line segment beyond A and B. A line does not have an endpoint.
Opposite angle : In a quadrilateral an opposite angle is the angle at the opposite corner of the corner where the angle is located.
Opposite side : In a quadrilateral the opposite side of a side refers to the side that does not share a corner with the original side.
Perpendicular line : Two lines are called perpendicular if they cross in a right angle.
Point : A point is an element in a space. Shapes are made of sets of points.
Quadrilateral : A quadrilateral or quadrangle is a polygon with four corners. Rectangles, trapezoids, kites, rhombuses, squares and parallelograms are all specific kinds of quadrilaterals. The sum of the interior angles in a quadrilateral is always $360^{\circ}.$
Rhombus : A rhombus is a quadrilateral that has four equal length sides. Every rhombus is a parallelogram.
Straight angle : A straight angle is an angle equal to $180^{\circ}.$
Theorem : A mathematical result that has been proven to hold true under the assumptions that are stated in the theorem. The most famous theorems have name like for example the Pythagorean theorem or Fermat's little theorem.
Triangle : A triangle is a polygon with three corners and three sides. You can calculate the area of a triangle by multiplying half the length of the base by the height on that base. The sum of the interior angles in a triangle is always $180^{\circ}.$
A quadrilateral ABCD is called cyclic if all of its points lie on a circle. Choose all statements that are true for a cyclic quadrilateral.
Intersect : Two shapes intersect if they have at least one point in common.
Line segment : A line segment AB is a one-dimensional shape consisting of the points A and B and all the points on the straight connection of A and B. A and B are both endpoints of the line segment AB.
Midpoint : The midpoint of a line segment is the point on the line segment that cuts the line segment into two equal length pieces.
Ratio : A ratio is a comparison of two numbers using a division.
Right triangle : A right triangle is a triangle that has a right angle. The sides that form the right angle are called legs, the third side is called hypotenuse. The area of a right triangle is half the product of the lengths of the two legs. The Pythagorean theorem is an important theorem for right triangles that allows to calculate the third side of a right triangle given the other two.
We look at a triangle with corners A,B and C. We call the sides opposite of A,B and C a, b and c and the midpoints of a,b,c D,E and F. Select all the statements that are true.
Parallel : Two lines in a two-dimensional plane are called parallel if they never cross.
Similar triangle : A similar triangle is a triangle with the same shape but not necessarily the same size. Ratios of corresponding side lengths and corresponding angles are the same in similar triangle. This fact is used to be able to uniquely define the trigonometric functions using ratios of side lengths in right triangles. Two triangles are similar if they share two angles (and therefore all three) or if all 3 ratios of the lengths of corresponding sides in the two triangles are the same. Two triangles are also similar if two ratios of lengths of corresponding sides in the two triangles are the same and the angle between the two sides in the two triangles is the same.
A line PQ and a line XY cross each other in a point O. Choose all statements that are true if the line PX is parallel to the line QY.