Give the exact value of each expression?

Question

8. (tan345°+tan75°)/(1-tan345°tan75°)
9. (tan 7π/2-tan 5π/2)/(1+tan 7π/2 tan 5π/2)
10. cos350°cos200°+sin350°sin200°

Answer 1

8) The expression is

Compare it to trigonometric formula

A = 345^o, B = 75^o

In first quadrant tangengent is positive.

From trigonometric table

 

Answer 2

9) The expression

Compare it to trigonometric formula

From trigonometric table

Answer 3

10)The expression

Compare it to trigonometric formula 

In second quadrant cos is negitive.

From trigonometric table