Question

prove that;tan25°+tan20°+tan25°tan20°=1​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

Let 25 ° = A and 20° = B then,

We know that tan(A+B) = tan A + tan B/1-tanA*tanB

So, tan (20+25) = tan 20 + tan 25/1-tan 20*tan 25

As tan (45) = 1

1 = tan 20 + tan 25 /1-tan 20 * tan 25

1-tan 20 * tan 25 = tan 20 + tan 25

So,

1 = tan 20 + tan 25 + tan 20 * tan 25