1st F ch13 ANGLES

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 2

CH4 Similarity

Types of angles

Acute angle: between 0° and 90°
Right angle: 90°

Obtuse angle: between 90° and 180°

Straight angle: 180°
Full angle: 360°           (A full angle is also called a full turn)

Both a straight angle and a full turn look like a straight line. The arc is used to show it is an angle.

Opposite angles

Opposite angles are the angles on opposite sides of the point of intersection of two lines. Opposite angles are always equal.

Calculating angles

Calculate the size of all angles.

Calculating angles

Calculate the size of all angles.

Sum of the angles

The sum of the three angles in a triangle is 180°
The sum of the four angles in a quadrilateral is 360°

∠A+∠B+∠C=180°

∠D+∠E+∠F+∠G=360°

Calculating angles

Calculate the size of angle C.

Calculating angles

Calculate the size of angle C.

∠C=180−82−60=38°

Special triangles

In an equilateral triangle, all sides are the same length and all angles are 60 degrees.

In an isosceles triangle, two sides are the same length and two angles are the same size.

Homework Monday

- Make and correct: R1, R3, R4, R5, R6

- Bring your calculator (every lesson!)