Question

Without using a calculator, find the values of the following expressions. (Give the answers in surd form if necessary.)
(a) sin270°=?
(b) tan360°=?
(c) cos180°=?

how to calculate?

Answer 1

which one you have doubt with ?

Answer 2

all. i can get the answer by using the calculator, but i don't know how to calculate them without it.

Answer 3

Can I right 270 as 360 - 90 ?

Answer 4

@kryton1212 , please reply.

Answer 5

yup

Answer 6

So I can also right : \(\sin 270 = \sin ( 360 - 90 ) \)

Correct?

Answer 7

yup

Answer 8

Ok! Take your time

Answer 9

Good , now we have :

the expression of the form \(\sin (360 - \theta)\)

You know the formula for sin(360 - theta) ?

Answer 10

-sinθ

Answer 11

Great work. So \(\sin (360 - 90 ) = ? \)

Answer 12

-sin90 ?

Answer 13

-1?

Answer 14

EXCELLENT!

Answer 15

Ok! Do you know what is the value of \(\sin 360 \) and \(\cos 360\) ?

Answer 16

it should be tan360

Answer 17

0 and -1 respectively

Answer 18

since, 360 =0, if you know tan 0, that will also do.

Answer 19

Yes, alomost. \(\cfrac{\sin 360}{\cos 360} = \tan 360\)

But here I am talking for the values of sin 360 and cos 360.

Answer 20

Sin 360 = 0 is right but cos 360 = 1 not -1

Answer 21

yup

Answer 22

cos180=-1