$$a^3-b^3=a^3-3ab+b^3$$

$$\left(a-b\right)^3=a^3+3a^2b^2-b^3$$

$$a^3-b^3=\left(a-b\right)\left(a^2+2ab+b^2\right)$$

$$a^3-b^3=\left(a-b\right)\left(a^2+ab+b^2\right)$$

$$\sin^2\alpha$$

$$\cos^2\alpha$$

$$tg^2\alpha$$

$$\operatorname{ctg}^2\alpha$$

$$\left(a-b\right)^2=\left(a-b\right)\left(a+b\right)$$

$$a^2-b^2=\left(a-b\right)\left(a+b\right)$$

$$a^2-b^2=a^2-ab-b^2$$

$$a^2-b^2=\left(a-b\right)\left(a+b\right)$$

$$a^3+b^3=a^3+3ab+b^3$$

$$\left(a+b\right)^3=a^3+3a^2b^2+b^3$$

$$a^3+b^3=\left(a+b\right)\left(a^2-2ab+b^2\right)$$

$$a^3+b^3=\left(a+b\right)\left(a^2-ab+b^2\right)$$

$$\sin^2a-\cos^2a=1$$

$$\sin^2a+\cos^2a=1$$

$$\sin a+\cos a=1$$

$$\sin^2a+\cos^2\beta=1$$

$$\operatorname{ctg}\alpha=\frac{\sin\alpha}{\cos\alpha}$$

$$\operatorname{ctg}\alpha=\frac{\cos\alpha}{\sin\alpha}$$

$$\operatorname{ctg}\alpha=\frac{1}{\operatorname{ctg}\alpha}$$

$$\operatorname{ctg}\alpha=\sqrt{1-tg\alpha}$$

$$tg\ \alpha\cdot\operatorname{ctg}\alpha=1$$

$$tg\ \alpha+\operatorname{ctg}\alpha=1$$

$$tg^2\ \alpha+\operatorname{ctg}^2\alpha=1$$

$$tg^2\ \alpha\cdot\operatorname{ctg}^2\alpha=1$$

$$\left(a+b\right)^2=a^2+ab+b^2$$

$$a^2+b^2=\left(a+b\right)\left(a+b\right)$$

$$\left(a+b\right)^2=a^2+2ab+b^2$$

$$a^2+b^2=a^2+2ab+b^2$$

$$P_n=\frac{n!}{n}$$

$$P_n^k=\frac{n!}{k!}$$

$$P_n=n!$$

$$P_n=\frac{n!}{2}$$

-1

0

2

1

sin A cos B + cos A sin B

sin A cos B - cos A sin B

cos A cos B - sin A sin B

cos A cos B + sin A sin B

$$2\cos\ \frac{\alpha+\beta}{2}\ \cos\ \frac{\alpha-\beta}{2}$$

$$2\sin\ \frac{\alpha+\beta}{2}\ \cos\ \frac{\alpha-\beta}{2}$$

$$-2\cos\ \frac{\alpha+\beta}{2}\ \cos\ \frac{\alpha-\beta}{2}$$

$$-2\sin\ \frac{\alpha-\beta}{2}\ \cos\ \frac{\alpha+\beta}{2}$$

$$2\sin\alpha\ \cos\alpha$$

$$2\sin\ \frac{\alpha}{2}\ \cos\ \frac{\alpha}{2}$$

$$\cos^{2\ }\alpha-\sin^2\alpha$$

$$\cos^2\ \frac{\alpha}{2}-\sin^{2\ }\ \frac{\alpha}{2}$$

$$\frac{2tg\alpha}{1-tg^2\beta}$$

$$tg\alpha\ tg\beta\pm tg\beta\ tg\alpha$$

$$\frac{tg\alpha\pm tg\beta}{1\pm tg\alpha\ tg\beta}$$

$$\frac{tg^2\alpha\pm tg^2\beta}{1\pm tg^2\alpha\ tg^2\beta}$$

$$\frac{\sqrt[]{3}}{2}$$

1

$$\frac{1}{2}$$

- $$\frac{1}{2}$$

$$\sin\ 45$$

$$\cos\ 45$$

$$\sin\ 71$$

$$\cos\ 71$$

$$a^3\pm b^3=\left(a\pm b\right)\left(a^2\pm ab\pm b^2\right)$$

$$\left(a\pm b\right)^3=a^3\pm3a^2b+3ab^2\pm b^3$$

$$a^3\pm b^3=a^3+3a^2b^2\pm b^3$$

$$a^3\pm b^3=\left(a^3+b^3\right)\left(a^3-b^3\right)$$

1 и 2

3 и 4

1 и 3

2 и 4

sin x + cos x

cos x - sin x

-sin x - cos x

- cos x +sin x

cos 50

sin 25

tg 25

cos 25

$$С_n^k=\frac{n!}{\left(n-k\right)!}$$

$$С_n^k=\frac{n!}{k!\left(n-k\right)!}$$

$$С_n^k=\frac{n!}{k!}$$

$$С_n^k=\left(n-k\right)!$$

380

190

18

22

$$A_n^k=\frac{n!}{\left(n-k\right)!}$$

$$A_n^k=\frac{n!}{k!\left(n-k\right)!}$$

$$A_n^k=\frac{n!}{k!}$$

$$A_n^k=\left(n-k\right)!$$

$$a_n=\ a_1+\frac{d}{2}$$

$$a_n=a_1\cdot d^n$$

$$a_n=a_1+\left(n-1\right)d$$

$$a_n=a_1+\left(n-2\right)d$$

$$b_n=\ b_1+\frac{q}{2}$$

$$b_n=b_1\cdot q^{\left(n-1\right)}$$

$$b_n=b_1+\left(n-1\right)q$$

$$b_n=b_1+\left(n-2\right)q$$

$$S_n=\frac{a_1+a_2}{2}$$

$$S_n=\frac{a_1+a_n}{2}\cdot d$$

$$S_n=\frac{a_1+a_n}{2}\cdot n$$

$$S_n=\frac{b_1\left(1-q^n\right)}{1-q^n}$$

50

42

8

60

$$S_n=\frac{b_1\cdot b_2}{2}$$

$$S_n=\frac{b_1\cdot b_n}{2}\cdot q$$

$$S_n=\frac{b_1+b_n}{q}\cdot n$$

$$S_n=\frac{b_1\left(1-q^n\right)}{1-q^n}$$

-1

2

-5

1