Question

if cot A = 1/4 and cot B = 1/5,then cot ( A+ B)​

Answer 1

Answer:

cotA=2

cotB=3

⇒A=tan

−1

2

1

⇒B=tan

−1

3

1

⇒A+B=tan

−1

2

1

+tan

−1

3

1

=tan

⎝

⎜

⎜

⎜

⎛

1−

2

1

3

1

2

1

−

3

1

⎠

⎟

⎟

⎟

⎞

=tan

−1

⎝

⎜

⎜

⎜

⎛

6

5

6

5

⎠

⎟

⎟

⎟

⎞

=tan

−1

1

A+B=

4

π