Question

tan25° + tan 20° + tan 25°.tan 20°​

Answer 1

Answer:

Value is 1

Step-by-step explanation:

$tan(25 + 20) = \frac{tan25 + tan20}{1 - tan25tan20}$

$tan45 = 1 = \frac{tan25 + tan20}{1 - tan25tan20}$

$tan25 + tan20 = 1 - tan25 \: tan20$

$tan25 + tan20 + tan25 \: tan20 = 1$