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Lekcja 4 A

DLA LEKTORA

SJO PW - Język angielski ogólnotechniczny, Poziom B2

Opracowanie: I. Zamecznik, M. Witczak, H. Maniecka, A. Hilgier, B.Przybyła, E. Fronc

GEOMETRY AND MEASUREMENT

Geometrie Figures - Two-Dimensional Geometry

Task 1. Point and lines, angles, triangles, quadrilaterals, polygons and the circle

i. Point and Lines:    Read the following sentences and choose the appropriate word in each pair.

A straight linę is a particular set/combination of points.

Two lines which lie in the same piane and which do not intersect, i.e. they do not share one common point are called perpendicular/parallel lines. They remain the same distance apart at all times.

Two lines that intersect and form right angles are called perpendicular/parallel lines.

ii. Angles:    Look at the attached glossary and match the name to the angle.

a)    An obtuse angle

b)    A right angle

c)    An acute angle

Triangles

ABC is a triangle. It has three equal angles and three equal sides.

A triangle that has three equal sides is called an equilateral triangle.

ABC is an isosceles triangle. It has two equal sides (AC and CB). When a triangle has two equal sides then it also has two equal angles.

All triangles can be classified into three categories: acute (-angled) triangles, obtuse (-anglcd) triangles, right (-anglcd) triangles.

Two triangles may be called similar only if their corresponding angles are congrucnt and their corresponding sides are proportional in length.

iii.    Quadrilaterals and Polygons

Polygons can be divided into regular polygons (when a polygon has all sides and all angles cqual), and irregular polygons. We can also describe polygons as convex or concave. A convex polygon is a polygon that has all interior angles less than 180°. A polygon that has one or morę interior angles greater than 180° is concave.

iv.    The circle:    Choose the correct word in each pair.

All points on the circle are equidistant from the centre. The distance across a circle through the centre is called the diameter / radius. The diameter / radius of a circle is the distance from the centre of a circle to any point of the circle. The diameter / chord of a circle is twice as long as the radius - so it is as long as two radii. The diameter chord is a linę segment that joins two points on a curve. A circle can have many different diameters / chords - but if the diameter chord passes through the centre it is called the diameter chord / radius.

The area of a circle equals rtr² where r is the radius. The perimeter of a circle is called the circumference. The circumference is calculated by the formula C=27tr, where r is the radius.

1.    It measure morę than 0° but less than 90°. (90 degrees)

2.    It measures morę than 90° and less than 180°.

3.    It measures 90°.

a.    A right angle (3)

b.    An acute angle (1)

c.    An obtuse angle (2)

Task 2. Match the angle names a, b, c to their descriptions 1, 2,3

Task 3.

Choose the word in italics that fits the follow ing sentences describing pictures on the right.

ABC here is a/an acute/obtuse/right triangle because all the angles are acute/obtuse.

ABC is a/an acute/obtuse/rieht triangle because one of the angles is a right angle.