Prepared by: Kuzhilnyy Artem , Skorkin Danil , Bordun Nastya , Dudko Helena , Kurbatova Yana , Oreva Sophia , Pestrikova Tanya , Derabina Darya, Gureev Yaroslav, Bodrykh Andrey , Evdokimova Nastya , Grizkova Marina.

Presentation on the topic:Lines and angels

Straight line – line. Angle - the geometric figure formed by two rays emanating from a single point. Segment - two points on the plane, connected by a straight angle - roughly speaking, two

rays emanating from a single point.

Perpendicular lines, rays, segment

View angleDifferences from the line segment

RememberAngles are measured in degrees (°). There are 360° in a full circle.

Types of angles

90 ° is a right angle

Acute angles are lessthan 90 °

Obtuse angles are between90 ° than 180 °

A straight line is 180 °

1+2=180 ° c+a+b=180°

Angles on a straight line add to 180° All the angles of triangle add up tо 180°

НExample

Blue lines – Perpendicular linesRed lines – Parallel lines

Parallel lines - straight lines , that are the same distance apart from each other all the way along their length . Even if the lines are made longer , they will never meet.

Perpendicular lines – lines that meet at a right angle .

Set Square – mathematical instrument that we use for measuring and drawing right angels , but we also use it for painting parallel and perpendicular lines .

Parallel and perpendicular lines

ExercisesLook at the pictures below. Decide whether the red lines are parallel or perpendicular.

perpendicular parallel

parallel

perpendicular

Write whether each angle is acute, obtuse or a right angle

Drawing anglesRule:

Before using a protractor to draw an angle, imagine what the angle will look like.Firstly, draw a single base line. Then, line up the protractor so that the centre is at one end, whichever one you wish to be the vertex of the angle.

Drawing anglesPractice:

1.Use a protractor to draw each of these angles.

a)60° b)12° c)141° d)89° e)179°

2.Remember! All the angles in a triangle add up to 180°.Use a protractor to draw triangles with these angles.

a)70° ,50° and 60° b)40° , 50° and 90° c)100° , 40° and 40° d)30° ,70° and 80°

Measuring angles Angles are measured with a tool called protractor. Angles are measured in degrees. The symbol for degrees is a little circle °. How to measure an angle with a protractor:● Place the midpoint of the protractor on the VERTEX of the angle.● Line up one side of the angle with the zero line of the protractor (where you see the number 0). ● Read the degrees where the other side crosses the number scale.

Thank you for your attention!