Posted by Anonymous on Wednesday, November 12, 2008 at 7:57pm.
from sin A = 1/2, cos A >0, we know that A has to be in quadrant I, so cosA = √3/2
from tan B = 3/4, and sinB<0, we know that B must be in quadrante III, so sinB=-3/5 and cosB = -4/5
Cos(A-B) = cosAcosB + sinAsinB
= √3/2(-4/5) + 1/2(-3/5)
= (-4√3 - 3)/10
Related Questions
Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 &...
trig 26 - simplify to a constant or trig func. 1. sec ²u-tan ²u/cos &...
TRIG - what is another form of: sin (A+B) sin (A-B)/ cos^2 A cos^2 B a) cos^2 A...
Trig. - tan^2BeatacscBeta-tan^2 (simplify) (sin/cos)^2Beta times 1/sin-(sin/cos...
trig - if point P is a point on the terminal side of 0, and 0 is in standard ...
math - prove these identies sin^2+tan^2=sec^2-cos^2 sin^2 sec^2 +sin^2=tan^2+...
Trigonometry - 1.Solve tan^2x + tan x – 1 = 0 for the principal value(s) to...
pre calc - The terminal side of an angle in standard position goes through the ...
trig - FInd the exact value pf the 6 trig function of alpha Given: point (-2,-6...
trig - it says to verify the following identity, working only on one side: cotx+...
For Further Reading
