anonymous
  • anonymous
how wud u solve the following? \[\cos (\tan^{-1} (-5/12)+\tan^{-1} (15/8))\] Plz help this is in 15 min!
Trigonometry
  • Stacey Warren - Expert brainly.com
Hey! We 've verified this expert answer for you, click below to unlock the details :)
SOLVED
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
jamiebookeater
  • jamiebookeater
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
anonymous
  • anonymous
ok do the numbers (5,12, ) and (8,15, ) remind you of something?
anonymous
  • anonymous
these numbers appear in the problem for good reason
anonymous
  • anonymous
umm im not sure way u mean

Looking for something else?

Not the answer you are looking for? Search for more explanations.

More answers

anonymous
  • anonymous
ok let me fill in the blanks: (5,12,13), (8,15,17). do these numbers look familiar?
anonymous
  • anonymous
these r (x y r) values?
anonymous
  • anonymous
pythagorean triples. i.e. integer side lengths for right triangles
anonymous
  • anonymous
ok then wat do i do w/this #?
anonymous
  • anonymous
don't mean to rush but this is due online in 10 min exactly
anonymous
  • anonymous
so you know [\tan^{-1} (-5/12)] refers to the 5,12,13 triangle, and [\tan^{-1} (15/8)] refers to the 8,15,17 triangle
anonymous
  • anonymous
ugh sry not familiar with the mathtype syntax here... i apologize for poorly formatted equations
anonymous
  • anonymous
its ok don't worry bout its understandable
anonymous
  • anonymous
now the 2 inverse tangents give you to angles. let's call them a and b. the angle a comes from the 5,12,13 triangle, and the angle b comes from the 8,15,17 triangle
anonymous
  • anonymous
draw your triangles, and identify which angle is a, and which angles is b
anonymous
  • anonymous
now back at the original equation, since i'm lazy and don't want to write out all the inverse tangents, i'll just write a and b: cos(a+b) = cos(a) cos(b) - sin(a) sin(b)
anonymous
  • anonymous
from your triangles, you should be able to identify what cos(a), cos(b), sin(a), and sin(b) are
anonymous
  • anonymous
so y for the 1st one is 5 n x is 12 while the 2nd y is 15 n 2nd x is 8?
anonymous
  • anonymous
|dw:1353483877024:dw|
anonymous
  • anonymous
sry, diagram not drawn to scale
anonymous
  • anonymous
thats fine but I'm still stuck :(
anonymous
  • anonymous
ok back to original equation remember a = tan-1(5/12) and b = tan-1(15/8) so the original equation: cos(a+b), can be expanded as cos(a)cos(b) - sin(a)sin(b)
anonymous
  • anonymous
now look at the pictures, what's cos(a)? what's cos(b)? what's sin(a)? what's sin(b)? (remember cos is adjacent/hypotenuse, sin is opposite/hypotenuse)
anonymous
  • anonymous
you should make a change of variables

Looking for something else?

Not the answer you are looking for? Search for more explanations.