Geometry

Quadrangle- Shape, which has 4 sides and 4 angle.- The sum of the measures of the interior angles of any quadrangle is 360 °.

Thrapezium- Thrapezium has at least a pair of parallel sides.- Sum of thrapezium’s angles, lying at the same arm is equal to 180o.- Formula to calculate the area:

P - areaa - lenght of higher baseb - lenght of lower baseh - height

- An isosceles thrapezium’s diagonals intersect at right angles.

2)( hbaP

Parallelogram- Parallelogram is a thrapezium.- It has 2 pair of parallel sides.- His parallel sides have the same length.- His diagonal intersect in half of their length.- Formula to calculate the area:

P - areaa - lenght of baseh - height

haP

Rhomboid- Rhomboid has 2 pair sides of the same lenght.- Sides of the same length are in contact with.- Angles between sides of different length are the same.- Formula to calculate the area:

P - areae - first diagonalf - second diagonal

2feP

Rhombus- The sum of two adjacent angles is equal to 180o.- The diagonals intersect at an right angle and divide rhombus into four right-angled triangles.- His sides are the same.- Formula to calculate the area:

feP P - areae - first diagonalf - second diagonal

Rectangle- Rectangle has 2 pair sides of the same lenght.- His diagonals are the same.- All angles of rectangle have 90o.- Rectangle has 2 pairs of parallel sides.- Formula to calculate the area:

baP P - areaa - first sideb - second side

Square-All angles are right.-All sides are the same.-His diagonal intersect at right angles.-His diagonals are the same.- Formula to calculate the area:

2aP Formula to calculate the diagonal:

2ad P – areaa – sided - diagonal

Triangle- Triangle has 3 sides.- Sum of his angles is equal to 180o.

Types:Classification by the sides:- a scalene triangle – all his sides have different length.- an isosceles triangle – both arms have the same length.- an equilateral triangle – all his sides have the same lenght.

Classification by the angles:- an acute-angled triangle – has 3 acute angles.- an right-angled triangle – has 1 right angle and 2 acute angles.- an obtuse-angled triangle – has 1 obtuse angle and 2 acute angles.

Formula to calculate the area:

2haP

P - areaa - baseh - height

Equilateral triangle- All sides have the same lenght.- All angles are equal to 60o.- Formula to calculate the area:

432aP

- Formula to calculate the height:

23ah P - area

a - sideh - height