Question

If tan(145) = -1/1.43 , what is tan(-125) A. -1.43, B. 1.43, C. 1/1.43, D. -1/1.43

Answer 1

tan (-125) = tan 235 = 1.42815
tan 145 = -1/143 = -0.70

1.42815 = -1/-0.70

so answer is 1.43

Answer 2

B. 1.43

Explanation:

Because tan (180-θ)=-tan θ

`tan (145) = tan (180 -35)= -tan 35 = -(1)/(1.43)\\tan 35 =(1)/(1.43)`

Because tan (90+θ) = -cot θ

tan (-125) can be written as:

`tan(-125)=-tan (125) = - tan (90+35) = cot 35`

tan θ x cot θ =1

⇒tan 35 x cot 35 = 1

⇒
`(1)/(1.43) * cot 35 =1 \\ cot 35 = 1.43`

⇒
`tan(-125)= cot 35 = 1.43`