Posted by Anonymous on Thursday, January 20, 2011 at 2:55am.
cos A = -4/5 for angle A in Quadrant II, find sin 2A
trig - Henry, Friday, January 21, 2011 at 7:13pm
cosA = -4/5 = -0.80,
A = 143.1deg.
sin(2A) = 2*sinA*cosA,
sin2A = 2*sin(143.1)*cos(143.1 =
trig - Henry, Friday, January 21, 2011 at 7:38pm
Solution using Exact values.
cosA = -4/5 = x/r.
(-4)^2 + Y^2 = 5^2,
16 + Y^2 = 25,
Y^2 = 25 - 16 = 9,
Y = 3.
SinA = Y/r = 3/5.
sin2A = 2 * 3/5 * -4/5 = -24/25.
Answer This Question
More Related Questions
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- Trig - Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are ...
- Trig - Find cos(s+t) if cos s= -1/2 and sin t= 3/5, s and t are in quadrant II. ...
- trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
- Trig - 1. Given Sin(A) = ⅗ and Cos(B) = 8/17 in Quadrant I, find Sin(A+B...
- trig - cos A = -4/5 for angle A in Quadrant II, find sin 2A
- Trig - If angle A is 45 degrees and angle B is 60 degrees. Find sin(A)cos(B), ...
- trig - what angle in degrees am i if the following is true: sin t > cos t if ...
- trig - can someone please help me with this problem. i'm doing my review right ...
- mth, trig - Given cos a=-7/25 in quadrant II , and sin b=-12/13, in quadrant IV...