Need help with finding exact values

sk8erboi

New member
Joined
Jan 29, 2018
Messages
8
Hey,

we're learning trig identities in school and finding exact values just makes no sense to me anymore. i was wondering if someone could help me - or at least point me in the right direction - with solving this:

Find the exact value of the following:

tan(7π/12)
sin105°


Thanks in advance
 

Subhotosh Khan

Super Moderator
Staff member
Joined
Jun 18, 2007
Messages
18,183
Hey,

we're learning trig identities in school and finding exact values just makes no sense to me anymore. i was wondering if someone could help me - or at least point me in the right direction - with solving this:

Find the exact value of the following:

tan(7π/12)
sin105°


Thanks in advance
Do you know the exact values of:

tan(π/4)

tan(π/3)

tan(A+B)

sin(45o)

sin(60o)

sin(A+B)
 

sk8erboi

New member
Joined
Jan 29, 2018
Messages
8
Do you know the exact values of:

tan(π/4)

tan(π/3)

tan(A+B)

sin(45o)

sin(60o)

sin(A+B)
yeah

tan(π/4) = 1

tan(π/3) = square root of 3

tan(A+B) = (tanA + tanB)/(1 - tanAtanB) .................Those parentheses are super important

sin(45o) = √2/2

sin(60o) = √3/2

sin(A+B) = sinAcosB + cosAsinB

What do i do from there though?
 
Last edited by a moderator:

Subhotosh Khan

Super Moderator
Staff member
Joined
Jun 18, 2007
Messages
18,183
yeah

tan(π/4) - 1

tan(π/3) - square root of 3


tan(A+B) - tanA + tanB/1 - tanAtanB

sin(45) - √2/2

sin(60º]) - √3/2

sin(A+B) - sinAcosB + cosAsinB

What do i do from there though?
Notice:


π/4 + π/3 = 7π/12

and

45º + 60º = 105º

What do you think you should do now?
 

sk8erboi

New member
Joined
Jan 29, 2018
Messages
8
Notice:


π/4 + π/3 = 7π/12

and

45o + 60o = 105o

What do you think you should do now?
OHH. I figured out the sin105 question, but the tan 7pi/12 question tripped me up. Now i feel stupid lmao thank you so much though
 

Jomo

Elite Member
Joined
Dec 30, 2014
Messages
3,276
Khan told you that π/4 + π/3 = 7π/12, you know the formula for tan(a+b) and you know the value of know tan(π/4) and tan (π/3)? So use this information in the formula for tan(a+b)
 
Top