sina cosa 60 169 a belongs to 45 degrees 90 degrees. Finding the values of sin and cos?

Solution: Because a (45°,90°) so: sina cosa, sina cosa, sina + cosa 0, sina-cosa 0 so:

sina-cosa)=sina+cosa-2 sina·cosa=1-2 sina·cosa=49 169 Therefore: sina-cosa=7 13 Therefore: (sina+cosa)=sina+cosa+2 sina·cosa=1+2 sina·cosa=289 169 Therefore:

sina + cosa = 17 13 2 sina = 24 13, therefore: sina = 12 13 -2 cosa = 10 13, therefore: cosa = 5 13

First of all, it is important to know that the square of sina + the square of cosa = 1 and the square of (sina + cosa) = the square of sina + the square of cosa + 2sinacosa In this way, you can find the value of sina + cosa 17 13 The problem is equivalent to the equation system of x+y=17 13 and xy=60 169, and a is to limit the value of sin and cos, so the value of sin is 12 169, and the value of cos is 5 169

If a is regarded as the first quadrant angle, then 90°+a is the second quadrant, and the cosine (cos) value of the second quadrant angle is negative, so there is a negative sign. Because 90 degrees is an odd multiple of 90 degrees, you have to change the trigonometric function, so you have to change it to sin. So the final answer is -sina.

Odd and even unchanged, symbols see quadrants).

sina-cosa=1 5,a[1,180 degrees],(sina-cosa) =sin a-2sinacosa+cos a=1-sin2a=1 25sosin2a=24 25sin(2a- 2) =sin( 2-2a) =cos2a because a[1,180 degrees] 2a belongs to (0,2) and, sin2a is greater than 0 so 2a(0, ) is classified and discussed; When 2a (0,..

sina + cosa) 2 = 1 + sin2a = 1 25, so tongdong sin2a = -24 25, thus (cosa-sina) 2 = 1-sin2a=49 25, and 90 ° "local pei dry = a< = 135 °, so the hu in the middle of the hu with cosa-sina<0, cosa-sina = -7 5, so cos2a = (cosa-sina)(cosa+sina) = 7 25

Solution: cos2a=1-2sina2

sina=4/5

cos2a=1-2*16/25

then the radical journey. A belongs to (90° -180°) and is used for the use of cosasina 2 + cosa 2 = 1

sina=4/5

cosa=+/3/5

and a belongs to (90° -180°).

cosa = - 3 lead burn 5

cos2a = 2cosa 2-1 =2*9 25-1=-7 25 sun stool cos2a=cosa 2-sina 2=9 25-16 25=-7 25

Solution: cos2a=1-2sina2

sina = 4 and 5

Which stove takes cos2a = 1-2 16 25

25 25-32 25=-7 25

A is a 0 degree angle of stuffy plexus, reason: sina + sina = 2 (v2 2sina + v2 fight good 2cosa) = v2sin (a + 45) = 1 i.e. sin (a + 45) = 2 2 i.e. a + 45 = 45

The solution is if sina + cosa = 1

Knowing that sina = 1, cosa = 0 or return cosa = 1, sina = 0, so a = 2k or a = 2k + 2, k belongs to z

Therefore, the set of letters and hues of a is {a a=2k or a=2k + 2, and k belongs to the slippery world z}