Cambridge International Mathematics

320 Trigonometry (Chapter 15)

a tanμ=^47 ftanμ=

OPP

ADJ

g

) μ= tan¡^1

¡ 4

7

¢

) μ¼ 29 : 7 o fSHIFT tan ( 4 ¥ 7 ) EXEg

So, the angle measure is about 29 : 7 o.

b cosμ=

2 : 67

5 : 92

fas cosμ=

ADJ

HYP

g

) μ= cos¡^1

μ

2 : 67

5 : 92

¶

) μ¼ 63 : 2 o fSHIFT cos ( 2 : 67 ¥ 5 : 92 ) EXEg

So, the angle measure is about 63 : 2 o.

EXERCISE 15B.2

1 Find the measure of the angle markedμin:

abc

de f

gh i

2 Find all the unknown sides and angles in the following:

abc

3 Check your answers forxin question 2 using Pythagoras’ theorem.

7m

4m

q

HYP OPP

ADJ

2.67 km

5.92 km

HYP q

ADJ

OPP

3cm

2cm

q

7cm

4cm

q

9cm

6cm

q

3.2 m

5.6 m

q

3.4 m 4.5 m

q

3.1 km 2.7 km

q

4m

3m

q

7.2 mm

12.4 mm

q

4.7 km

5.2 km

q

8cm

5cm

f

q

xcm

9.45 km

12.06 km

ab

xkm

4.8 m

3.5 m

b

a

xm

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Y:\HAESE\IGCSE01\IG01_15\320IGCSE01_15.CDR Friday, 26 September 2008 3:10:20 PM PETER