Question

To verify the identity tan (x1+x2+x3) = tan x1 + tan x2 + tan x3 - tan x1 tan x2 tan x3 / 1 - tan x1 tan x2 - tan x2 tan x3

Answer 1

Answer:

The answer is the last one

$tan(x_{1}+x_{2}+x_{3})=\frac{tanx_{1}+tan(x_{2}+x_{3})}{1-tanx_{1}tan(x_{2}+x_{3})}$

Step-by-step explanation:

∵ $tan(x_{1}+x_{2}+x_{3}=\frac{tanx_{1}+tan(x_{2}+x_{3})}{1-tanx_{1}tan(x_{2}+x_{3})}$

$=\frac{tanx_{1}+\frac{tanx_{2}+tanx_{3}}{1-tanx_{2}tanx_{3}} }{1-tanx_{1}(\frac{tanx_{2}+tanx_{3}}{1-tanx_{2}tanx_{3}})}$

Multiply up and down by $1-tanx_{2}tanx_{3}$

$\frac{tanx_{1}(1-tanx_{2}tanx_{3})+tanx_{2}+tanx_{3}}{1-tanx_{2}tanx_{3}-tanx_{1}tanx_{2}-tanx_{1}tanx_{3}}$

$=\frac{tanx_{1}+tanx_{2}+tanx_{3}-tanx_{1}tanx_{2}tanx_{3}}{1-tanx_{1}tanx_{2}-tanx_{2}tanx_{3}-tanx_{1}tanx_{3}}$

Answer 2

Answer:

1. B, E

2. B, E

3. B

4. B

5. D

6. A

7. D

8. A

9. B

10. B

11. A

Step-by-step explanation: