Everything Maths Grade 10

5.Press ( 1 ÷ 4 ) cos 27 ) = 0,22275...0,22

OR

Press cos 27 ) = ANS ÷ 4 = 0,22275...0,22

6.Press ( 5 ÷ 6 ) tan 34 ) = 0,56209...0,56

OR

Press tan 34 = ANS × 5 ÷ 6 = 0,560,56

7.First writesecin terms ofcos:sec 34 °=

1

cos 34 °

(since there is no “sec” button on your calculator).

Press 1 ÷ ( cos 34 ) ) = 1,206217...1,21

8.First writecotin terms oftan:cot 49 °=

1

tan 49 °

(since there is no “cot” button on your calculator).

Press 1 ÷ ( tan 49 ) ) = 0,869286...0,87

Worked example 3: Calculator work using substitution

QUESTION

Ifx= 25°andy= 65°, use your calculator to determine whether the following statement is true or false:

sin^2 x+cos^2 (90°y) = 1

SOLUTION

Step 1: Calculate the left hand side of the equation

Press ( sin 25 ) ) x^2 + ( cos 90 − 65 ) ) x^2 = 1

Step 2: Write the final answer

LHS = RHS therefore the statement is true.

Exercise 5 – 2:

1.Use your calculator to determine the value of the following (correct to 2 decimal places):

a) tan 65 ° b) sin 38 ° c) cos 74 ° d)sin 12 °

e) cos 26 ° f) tan 49 ° g)sin 305 ° h) tan 124 °

i)sec 65 ° j) sec 10 ° k)sec 48 ° l)cot 32 °

m) cosec 140 ° n) cosec 237 ° o) sec 231 ° p)cosec 226 °

q)

1

4

cos 20 ° r) 3 tan 40 ° s)

2

3

sin 90 ° t)

5

cos4,3°

u)

p

sin 55 ° v)

sin 90 °

cos 90 °

w)tan 35 °+cot 35 ° x)

2 +cos 310 °

2 +sin 87 °

Chapter 5. Trigonometry 117