∫ 5sin7xcos7x dx =∫ (5/2) *2*sin7xcos7x dx=
(5/2) ∫ sin (2*<span>7x) dx=(5/2) *(1/14)*( - cos14x) + C = -(5/28)*cos14x +C.
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</span>∫( sin² 5x - cos²5x )dx = ∫ -(cos²5x - sin² 5x ) dx = ∫- cos(2*5x) ) dx =
- (1/10)*<span>sin10x +C .
</span><span>----------</span>
∫ (2 - 2sin² x )dx = ∫ 2(1 - sin² x) dx = ∫ 2cos² x dx = ∫ (1+cos2x)<span> dx =
x +(1/2 )*</span>sin2x +C .
Решение
<span>Ctg a= - 7/24 , 450<a<540
ctg</span>²<span>a + 1 = 1/sin</span>²a
<span>sin</span>²a = 1 / (ctg²a + 1)
<span>sin</span>²a = 1 / [(-7/24)² + 1] = 1 / [(49/576) + 1] = 576 / 625
sina = 24/25
<span>cosx = - </span>√(1 - sin²a) = - √(1 - 576/625) = - √49/625 = - 7/25
<span>sin</span>²(a/2) = (1 - cosa)/2 = (1 + 7/25)/2 = 32/(25*2) = 16/25
<span>sin(a/2) = 4/5
</span>
1.cos^2(\pi+t)+cos^2(\pi-t)=
=cos(\pi+t)*cos(\pi+t)+cos(\pi-t)*cos(\pi-t)=
=(-cos(t))^2+(-cos(t))^2=2cos^2(t)
2. cos(2\pi-t)-sin(3\pi/2+t)=1
cost+cost=1
2cost=1
cost=1/2; t=\pi/3
3. sin(2\pi-t)-cos(3\pi+t)-1=0
-sint-cos(\pi+t)=-1
-sint+cost=-1
sint-cost=1
sint [-1;1]; cos[-1;1] => sint=1: cost=0
t=\pi/2