It is known that a rsina 2cosa 10 and 2 tan2a

Solution: sina + 2cosa = 10 2, (sina + 2cosa) = sin a + 4cos a + 4 sinacosa

1+(3cos²a-3/2)+3/2+2sin2a5/2+3/2•cos2a+2sin2a

10/2)²=5/2，3/2•cos2a+2sin2a=0，tan2a=sin2a/cos2a=-3/4．

So the answer is: -3 4

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Implicit condition: sina squared + cosa squared = 1, by (sina + 2cosa) squared = 10 4 = 5 2, ie.

sina square + 4cosa square + 4sina * cosa = 5 2, piecing together:

sina square + cosa square) + 3 cosa square + 4 sina * cosa = 5 2

From 4sina*cosa=2sin(2a), 1+3cosa squared +2sin2a=5 2

Launch. 2sin2a = 3 2-3cosa squared = 3 2 * (1-2cosa squared) = -3 2cos2a

Launched, sin2a cos2a = -3 4

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According to the embroidery guide formula, we first find secant sec = 1 + tan =1 + 5 =26, sec = 26, cos =1 sec =1 ( 26), 2cos =2 [1 ( 26)] 2 26 = 1 13.

Because tana=2, the phase split state is cultivated in a right-angled triangle, the two right-angled edges are respectively , and the angles of the straight closed posture angular edges with a side length of 2 are a;

So sina = 2/5 of the root number 5, cosa = 5/5 of the root number

Substituting the formula, the original formula = 4x4 5-3x2 5-5x1 5=1

sin^2a+cos^2=1

tana=sina shirt sail spike cosa

Original = (2sin 2a-3sinacosa-2cos a) 1(2sin 2a-3sinacosa-2cos 2a) (sin 2a+cos 2a).

The numerator and denominator are divided by cos 2a, and the original formula = (2tan 2a-3tana-2) (tan 2a+1).

tana=2

or Bu Yuan car scale = (2 2 2-3 2-2) 5 = 0

The left formula is divided by 1, which is sin squared + cos squared, to get the fraction, and the top and bottom are divided by cos squared at the same time. The formula obtained is only related to tan.

The answer seems to be 0

Solution: sin a-2cos 2 3sin a-2cos 2sin a-2cos a 3sin a-2cos a(tan a-2) 3tan a-2

Put it again. tana = 2 substitution (tan a-2) 3tan scrambler a-2, you can get the fight:

Original formula = (tan a-2) 3tan slow silver lift a-2 In summary, sin a-2cos 2 3sin a-2cos 2 is 1 5

Knowing that tana=3 2, sin a+cos a=1, then 2sin a-3sinacosa-5cos a(2sin a-3sinacosa-5cos a) (sin a+cos a) The numerator and denominator are divided by cos a

2sin²a-3sinacosa-5cos²a) /cos²a]/[(sin²a+cos²a）/cos²a]

2tan a-3tana-5) (tan a+1) generation tana=3 2 solution:

Original formula = (2tan a-3tana-5) (tan a+1) If you don't understand, you can ask Helpful Thank you.

tan a =3

Original formula = (sin squared a + 3sinacosa+2 (cos squared a -sin squared a) (sin squared a -cos squared a) numerator denominator is divided by cos square a to get tan square a + 3 tana + 2 (1-tana) tan square a + 1 and then substituted.

tan（π+a）=tana=3

sin²a+3sinacosa+2cos2a=(sin²a+3sinacosa+2cos2a)/1=(sin²a+3sinacosa+1+cos²a)/(sin²a+cos²a)

2sin²a+3sinacosa+2cos²a)/(sin²a+cos²a)

Divide the fraction up and down by sin a at the same time

The formula becomes. =（2+3tana+2tan²a)/(tan²a+1)