Question

What is the exact value of cos(arcsin(1/4))? Kindly explain to me how. :)

Answer 1

first convert 1/4 into decimals
??@mathway

Answer 2

1/4= 0.25

Answer 3

now as we know sin 30 =0.5
so sin 15 = 0.25
now arcsin (0.25) = 15 degress okay ??
@mathway

Answer 4

Did you get it till now

Answer 5

Nothing comes up in my notifications. Sorry.

Answer 6

oh where you are having difficulty ?

Answer 7

Why did sin 30 become sin 15? Is it because we ant to get the half of it (to get 0.5)?

Answer 8

And I didn't know sin 30 =0.5. Yikes!

Answer 9

it is in table of trigonometry , you should remember the whole table yourself

sin 30 degree = 0.5
so
sin 15 degree = 0.25
okay ???

Answer 10

Since arcsin1/4 is equals to 15, we now need to get the cos of 15?

Answer 11

I was looking up for the tigro table, but I don't know which one is that. Could you please tell what it looks like? :)

Answer 12

yes
you are correct
arcsin (1/4) = 15
we need to know what is the value for cos 15
we do same for cos 15
as we do for sin 15
I mean first we take our the value of cos 30
which is
cos 30 =0.866
so what will be the value for cos 15
Tell me your self

Answer 13

Is it the half of 0.866?

Answer 14

yes

Answer 15

Also, is this the trigonometry table? https://www.google.com/search?q=table+of+trigonometry&rlz=1C1CHMO_enUS611US611&espv=2&biw=1517&bih=783&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMI76LS7e3gxgIVxCoeCh2KSgCX&dpr=0.9#tbm=isch&q=table+of+trigonometry+with+decimals&imgrc=ao8XQOd5IYy6OM%3A

Answer 16

and here is the table
https://www.google.com.pk/search?q=trigonometry+table+0-90&biw=1366&bih=659&tbm=isch&imgil=2xbrLGCsrMX9UM%253A%253BridUNDj2YryhWM%253Bhttp%25253A%25252F%25252Fwww.youtube.com%25252Fwatch%25253Fv%2525253DtyS0SPoi5dA&source=iu&pf=m&fir=2xbrLGCsrMX9UM%253A%252CridUNDj2YryhWM%252C_&usg=__QPUH5cIvtTDW1iz3C3WP0uRTSRk%3D&ved=0CCYQyjdqFQoTCLbZz-rw4MYCFQQ_FAodw_cG0w&ei=kUioVfbMNYT-UMPvm5gN#imgrc=tOTEJZ-k-SQXQM%3A&usg=__QPUH5cIvtTDW1iz3C3WP0uRTSRk%3D

Answer 17

So it is 0.433.

Answer 18

yes you are correct
Good job smart girl :)

Answer 19

Lol I'm really sorry if I seem dumb to you haha. I'm taking Pre-Calc and never took Trigonometry, so this topic is kinda new to me. But thank you so much for the help @Haseeb96 ! :)

Answer 20

oh well, I am here to sort out the problems of my friends
Whenever you need help in math or physics
you can tag me
If i will be able to solve that , I would have tried my best.
@mathway
Welcome again :)