Ответ:

A

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| \

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| ------ B

C

Объяснение:

1) cos B = BC/AB => AB = BC/cosB = 2/(2/3)= 3 см

AC = √(AB² - BC²)= √(3²-2²)= √5 cm

2) sin B = AC/AB => AB = AC/sinB= 3/(1/4)= 12 cm

CB= √(AB² - AC²) = √(12²-3²)= √135 cm = 3* √15 cm

3) tgB = AC/CB => CB = AC / tgB = 4/2 = 2 cm

AB = √(AC²+CB²) = √(4²+2²)= √20 cm = 2√5 cm

4) cosA= AC/AB => AC= cosA*AB= 5/8 * 8 = 5 cm

CB= √(AB²-AC²)= √(8²-5²)= √39 cm

1) = (√2/2)² - 1/2 = 2/4 - 1/2= 0

2) = 2*(√3/2)² + 1= 2* 3/4 + 1 = 6/4 +1= 6/4 + 4/4 = 10/4 = 5/2= 2,5