I have two problems

1)Express cot 138° 15' 10'' as the same function of a positive acute angle and then find its value.

2) Using exact values find the numerical value of tan 225°+tan(-45°)tan(-45°) is in 4th quadrant?

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- Mar 1st 2007, 03:11 AMAmyTwo Trigonometry Problems
I have two problems

1)**Express cot 138° 15' 10'' as the same function of a positive acute angle and then find its value.**

2) Using exact values find the numerical value of tan 225**°+tan(-45****°)**tan(-45°) is in 4th quadrant?

- Mar 1st 2007, 11:55 AMThePerfectHacker
- Mar 1st 2007, 12:05 PMThePerfectHacker

Use the identity tan(180°+x)=tan x for accute x.

Thus,

tan 225°=tan(180°+45°)=tan 45°=1.

For the second tangent, tan(-45°), use the identity,

tan(-x)=-tan x.

Thus, tan(-45°)=-tan(45°)=-1.

Thus,

1+(-1)=0.

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tan(-45°) is in 4th quadrant?

360°-45°=315°

Which is an angle in the 4th quadrant because,

270°<x<360°