Очень завтра уже будет поздно!

Сначала формулы . затем формулы двойного угла sin2α=2sinαcosα cos2α=cos²α-sin²α=cos²α-(1-cos²α)=2cos²α-1⇒  2cos²α=1+cos2α cos2α=cos²α-sin²α=1-sin²α-sin²α=1-2sin²α⇒  2sin²α=1-cos2α а) сos75°cos105°=cos(90°-15°)·cos(90°+15°)== sin15°(-sin15°)=-sin²15°=-(1-cos30°)/2=(cos30°-1)/2= ((√3/2)-1)/2=0,25√3-0,5б) sin75°sin15°=°sin(90°-15°)sin15°=cos15° sin15°=sin30°/2=1/4=0,25в) sin105°cos15°=sin(180°-75°)cos15°=sin75°cos15°=sin(90°-15°)cos15°=cos15°cos15°=(1+cos30°)/2=(1+(√3/2))/2=0,5 +0,25√3 2 способ формулы cosα·cosβ=0,5cos(α-β)+0,5cos(α+β) sinα·sinβ=0,5cos(α-β)-0,5cos(α+β) sinα·cosβ=0,5sin(α+β)+0,5sin(α-β) а) сos75°cos105°=0,5cos(75°-105°)+0,5cos(75°+105°)=0,5cos(-30°)+0,5 cos180°==0,5· √3/2+0,5·(-1)=0,25√3-0,5б) sin75°sin15°=0,5cos(75°-15°)-0,5cos(75°+15° )=0,5cos60°-0,5 cos90°=0,5·0,5=0,25в) sin105°cos15°=0,5sin(105°+15°)+0,5sin(105°-15°)= =0,5sin120°+0,5sin90°==0,5 sin(180°-60°)+0,5·1=0,5 sin 60°+0,5=0,25√3+0,5

Is there a garden around our house?
There isn't a garden around our house.

Is there a table and some chairs between the door and the window?
There isn't a table and some chairs between the door and the window.

Is there an armchair between the sofa and the cupboard?
There isn't an armchair between the sofa and the cupboard.

Is there a shirt and some sweaters on the shelf?
There isn't a shirt and some sweaters on the shelf.

Is there a long bench and a flowerbed in front of our house?
There isn't a long bench and a flowerbed in front of our house.

Are there some big empty buckets over there?
There aren't any big empty buckets over there.

Are there a lot of buses in front of the factory?
There aren't a lot of buses in front of the factory.

Are there two new cars behind the garden?
There aren't two new cars behind the garden.

Is there a new car in my yard?
There isn't a new car in my yard.

Are there many apples on apy dish?
There aren't many apples on apy dish.

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