Question

given sin 4/5 in quadrant 1 and cos -12/13 in quadrant 2 find cos (a+b)

Answer 1

someone please respond im going to get a major whipping if i dont

Answer 2

given cos -24/25 in quadrant 2 and sin -5/13 in quadrant 3 find sin (a+b)

Answer 3

a. 204/325
b. -36/325
c. -204/325
d. 36/325

these are the answers to the second question

Answer 4

u mean (cos a =-24/25) and (sin b=-5/13)?

Answer 5

yes

Answer 6

sin(a+b)=sina cosb + cosa sinb

Answer 7

we have cosa and sinb
so we need to find sina and cosb

Answer 8

we know that
\[\cos^2x+\sin^2x=1\]

Answer 9

yes please continue

Answer 10

\[\sin^2a=1-\cos^2a=1-(-24/25)^2=(7/25)^2\]

Answer 11

\[\sin a=\pm 7/25\]
we choose sin a =7/25 because a is in quadrant 2

Answer 12

so is the answer a? 204/325?

Answer 13

just like what we did for sina
\[\cos b=\pm12/13\]
we choose cosb =-12/13 because b is in quadrant 3

Answer 14

wait a sec

Answer 15

?

Answer 16

answer is d

Answer 17

tan5π/6+tanπ/61−tan5π/6tanπ/6

Answer 18

a. √3
b. 0
c. undefined
d. 1

Answer 19

@ap331 Please close this question and post the question as a new one when you ask another one :)

Answer 20

@ap331: its little confusing. can u write back again ??