Easy Trig question Help me plz

posted by .

can someone tell me the steps of answering this problem Sin(B+15)=Cos(2B+30) the answer is B=15 but im not sure how to get that answer, i thought u set B+15=2B+30 but i end up getting B= -15 when i do that.


You should know the basic relation between sine and cosine is
sin(x)=cos(90 -x) Thus
B+15 = 90 - (2B+30) so
3B +45 = 90 or
3B = 45 and B =45/3
No, you cannot just set them equal to each other.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. algebra

    Can someone please help me do this problem?
  2. math (trig)

    i have some problems doing trig the first one is: Show that cos(x/2) sin(3x/2) = ½(sinx + sin2x) i know that you are supposed to substitute all those trig function things in it but i kind of forgot how to the only that i can see substituting …
  3. Trig

    Solve in terms of sine and cosine: sec(x) csc(x)- sec(x) sin(x) so far I have: 1/cos(x) 1/sin(x) - 1/cos(x) sin(x) I am not sure where to go to from there. The book says the answer is cot(x) or cos(x)/sin(x) Thank you in advance.
  4. TRIG!

    Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6 x=1 - (3/4)sin^2 2x work on one side only! Responses Trig please help! - Reiny, Monday, February 23, 2009 at 4:27pm LS looks like the sum of cubes sin^6 x + cos^6 …
  5. trig

    The expression 4 sin x cos x is equivalent to which of the following?
  6. Math

    Solve this equation algebraically: (1-sin x)/cos x = cos x/(1+sin x) --- I know the answer is an identity, and when graphed, it looks like cot x. I just don't know how to get there. I tried multiplying each side by its conjugate, but …
  7. Precal

    I do not understand how to do this problem ((sin^3 A + cos^3 A)/(sin A + cos A) ) = 1 - sin A cos A note that all the trig terms are closed right after there A's example sin A cos A = sin (A) cos (A) I wrote it out like this 0 = - …
  8. Trig

    Find cos(s+t) if cos s= -1/2 and sin t= 3/5, s and t are in quadrant II. I got the answer to be -4/10 plus -3sqrt(3)/10. Is that right?
  9. Calculus 12th grade (double check my work please)

    1.)Find dy/dx when y= Ln (sinh 2x) my answer >> 2coth 2x. 2.)Find dy/dx when sinh 3y=cos 2x A.-2 sin 2x B.-2 sin 2x / sinh 3y C.-2/3tan (2x/3y) D.-2sin2x / 3 cosh 3yz...>> my answer. 2).Find the derivative of y=cos(x^2) …
  10. Math

    Hi! My teacher told my class that the answer to this question is "1-sin x/cosx" but she wants us to figure out why. I tried solving it but I didn't end up with the answer given. Can someone help me?

More Similar Questions