1.

) ~fam 40 LN gy %‘: )

Answer»

tan50= tan(40+10)

we have tan(a+b) = (tan a +tan b)/(1-tan a tan b)

= tan(40+10) = (tan40+ tan10)/(1-tan40tan10)

= tan50 = (tan40+ tan10)/(1-tan40tan10)

= tan50(1-tan40tan10)=tan40+ tan10

= tan50-tan50tan40tan10 = tan40+tan10

and tan50 = tan(90-40) = cot40

= tan50-cot40tan40tan10 = tan40+ tan10

= tan50-tan10 = tan40+ tan10

because cot40= 1/tan40

=tan50 = tan40+2tan10



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