1971-11-23 — Page 25

熱日僑華

育教頁一第張七第日六初月十年辛属夏

AH KIU YAT PO

二期星日三廿月一十年一七九一醫公年十六國民中

育教僑華

1912英文中學會考試題預習專欄

堅道英文書院主編

數學科

(四)

MATHEMATICS

(Lesson 4)

radius of the aro 38 is 1.5 in.

radius of the a aro PQ is 2.5 in.

Quadrant I-coordinate

nate

Jain Gos, tan

azsa or rug

+1) 6

· ©](x + 1)2

16 (27+

Mat

2nd

+

+

+

3rd

4th

To remember the above result, it is helpful to follow the adjacent diagram, using the word "cast" showing which ratio is positive in the various quadranta.

Solution to Exerolus

(1) Lat, AFH -5

then BPKA

AH Conno 6

(3) (1)

20 Como

BP

BK Cosmo:

30! Cosed

20" Cossa €

30 Conso

50-Cos60

But

BP- 70"

50" Corao

703.

Coseo

50

1869

88

Let and I be the two positions of the observera.

ДИВ

90

143 24

MN Cot XAN-

630 Cot(143°24' - 90°) yd.

630 Cot53° 24°

yd.

MN CoBeC MAN

630 Cosec. 53

784-734

143 24

630 yd.

Soluti

of the aro - [angle subtended

centre in radian

radius of the ar

"Ares of the factor

Lot

Than

180

Tadian

radian

135°

135

180°

Tadi an

(11)

radian

radian

480

135"

180

suppose IOP is obtuse

90°<

in the figure.

■ units:

៦ ....

1a(180°

18-acute

#in(180°

(0) π

radian

180

Analsansaster than a right angle

tan(180

180

(180

The definitions for sins, Cosine and so on given lesson one apply only to acute angles.. For angles

90 new definitions are required.

“Bimilar method

Bin(180

radius

OX and OY be the coordinate axGS

ith the

same scale.

Lot

adius)" z angle subtended

centre in radian

POX -4°

Then we

have the following

definitions for the

trigonometrical:

ration of

paordi

coordinate of P

"osordinate of P

coordinate of P

The signs of the trigonometrical ratios of when P is in the various quadrants are summarized in the following tables-

sin

COB B

can prove tha

-sin §°

Cos(180

tan(180°

tan

ain(360°)

Cost 360°

Ꮎ

COB

taff 360°

18135

Cos

#ia(180°

Cos(180

tan(180

0.707

-0.707

Brezoise 4

(1) Find the value of

(a)"

0.6

and Coa

Cos

Con D

and

arid: Bin

tan

-0.75

(2)

oin(p +ɣ) and (os (8 +ɣ

The angles of a triangle are

in terms:

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