mth, trig
posted by shay .
Given cos a=7/25 in quadrant II , and sin b=12/13, in quadrant IV , find cos(a+b) and sin2a

sin a = 24/25
cos b = 5/13
now apply addition formulas 
Thanks but how did you find that? My numbers came out completely different _

If a is in QII, sin is positive, cos is negative.
7^2 + 24^2 = 25^2, so it's a 72425 triangle
If b is in QIV, sin is negative, cos is positive.
5^2 + 12^2 = 13^2, so it's a 51213 triangle.
what did you do to find the missing sin/cos values?
Respond to this Question
Similar Questions

trig
can someone please help me with this problem. i'm doing my review right now and i'm stuck? 
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? 
Trig
find sin(s+t), given that sin t=1/3, t in quadrant 2, and cos s = 2/5, s in quadrant 3 
trig
Find cos(A+B). cos A=1/3 and sin B=1/2, with A in quadrant I and B in quadrant IV. 
Trig
Find sin(s+t) and (st) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are in quadrant 1. =Sin(s)cos(t) + Cos(s)Sin(t) =Sin(1/5)Cos(3/5) + Cos(1/5)Sin(3/5) = 0.389418 Sin(st) =sin(s)cos(t)  cos(s)sin(t) =sin(3/5)cos(1/5)  cos(1/5)sin(3/5) … 
Math
Find the exact value of the trig expression given that sin u = 5/13 and cos v = 4/5. u and v are in the second quadrant. cos(v  u) 
PreCal
Find sin 2x, cos 2x, and tan 2x from the given information. [1]. sin x = 8/17, x in Quadrant I 1). sin 2x =________. 2). cos 2x =________. 3). tan 2x =________. [2]. sin x = 5/13, x in Quadrant III 1). sin 2x =________. 2). cos 2x … 
Trig
1. Given Sin(A) = ⅗ and Cos(B) = 8/17 in Quadrant I, find Sin(A+B). a) 24/80 [b)] 84/85 c) 60/80 d) 60/85 Find Cos(A+B). a) 32/80 b) 45/85 c) 13/80 [d)] 13/85 Find Tan(A+B) a) 0.8 [b)] 1.72 c) 4.21 d) 6.46 I keep getting … 
Trig
Given Tan(A) = 5 in Quadrant III and Sin(B) = ⅔ in Quadrant II, find Cos(AB). 
Grade 12 Trigonometry
Angle a lies in the second quadrant and angle b lies in the third quadrant such that cos(a)=3/5 and tan(b)=24/7. Determine an exact value for a) cos(a+b) b) sin(ab) c) sin2a