Section 5 - Geometry And Measures Flashcards
Tell me the 5 simple rules of geometry
Angles in triangle add to 180 degrees
Angles on a straight line add up to 180
Angles in a quadrilateral add to 360
Angles on a round point add to 360
Isosceles triangle have 2 sides the same and 2 angles the same
Tell me about angles around parallel lines
The 2 bunches of angles formed at the points of intersection are the same
There are only 2 different angles involved and add to 180 on a parallel line
Vertically opposite angles are equal
Tell me about alternate angles
Alternate angles are the same and found in a Z shape
Tell me about allied/ interior angles
Allied angles add to 180 and found in a c or u shape
Tell me about corresponding angles
They are the same, found in an f shape
What’s 3 letter notation
Eg angle abc is referring angle formed at b - might see it as b with a little hat
What’s a polygon
Can be regular or irregular
A regular polygon is where all the sides and angles are the same
List some regular polygon names
Equilateral triangle Square Pentagon Hexagon Heptagon Octagon Nonagon Decagon
What are the sum of exterior angles in a polygon
For any polygon
360 degrees
How do you work out the sum of interior angles in a polygon
For any polygon
(N - 2) X 180
N= number of sides
How do you work out an exterior angle of a regular polygon
360 divided by n (number of sides)
How do you work out the interior angles in a regular polygon
180 - exterior angle
Tell me about equilateral triangles
3 equal sides
3 equal angles of 60 degrees
3 lines of symmetry
Rotation symmetry order 3 (how many turns on each side to do 360 degrees)
Tell me about right angled triangles
1 right angle
No lines of symmetry
No rotational symmetry
Tell me about isosceles triangles
2 sides are the same
2 angles the same
1 line of symmetry
No rotational symmetry
Tell me about scalene triangles
All 3 different sides
All three different angles
No symmetry
Tell me about squares
4 equal angles
4 lines lf symmetry
Rotational symmetry order 4
Diagonals are the same length and cross at right angles
Tell me about rectangles
4 equal angles
2 lines of symmetry
Rotational symmetry order of 2
Tell me about rhombus
Same as diamond, a square pushed over
4 equal sides
2 pairs of equal angles - opposite angles equal
Neighbouring angles add to 180
2 lines of symmetry and a rotational symmetry order 2
Diagonals cross at right angles
Tell me about parallelogram
A rectangle pushed over
2 pairs of equal sides
2 pairs of equal angles
- opposites equal and interior add to 180
No lines of symmetry
Rotational symmetry order of 2
Tell me about trapezium
1 pair of parallel sides
No lines of symmetry
No rotational symmetry
Tell me about kites
2 pairs of equal sides
1 pair of equal angles
1 line of symmetry
No rotational symmetry
Diagonals cross at right angles
Tell me the rules of a circle
A tangent and a radius meet at 90 degrees
2 radi form an isosceles triangle
The perpendicular dissector of a chord passes through the centre of the circle
The angle at the centre of the circle is twice the angle at the circumference
The angle in a semicircle is 90 degrees
Angles in the same segment are equal
The opposite angles in a cyclic quadrilateral add to 180
Tangents from the same point are the same length
Tell me about the alternate segment theorem
The angle between a tangent and a chord is always equal to the angle in the opposite segment