Find the Exact Value tan(105 degrees )

Problem

tan(105)

Solution

1. Identify two common angles from the unit circle that sum to 105

105=60+45

2. Apply the sum formula for the tangent function, which is tan(A+B)=(tan(A)+tan(B))/(1−tan(A)*tan(B))

tan(60+45)=(tan(60)+tan(45))/(1−tan(60)*tan(45))

3. Substitute the known values tan(60)=√(,3) and tan(45)=1 into the formula.

tan(105)=(√(,3)+1)/(1−(√(,3))*(1))

4. Simplify the expression.

tan(105)=(√(,3)+1)/(1−√(,3))

5. Rationalize the denominator by multiplying the numerator and denominator by the conjugate 1+√(,3)

tan(105)=((√(,3)+1)*(1+√(,3)))/((1−√(,3))*(1+√(,3)))

6. Expand the numerator and denominator.

tan(105)=(√(,3)+3+1+√(,3))/(1−3)

7. Combine like terms in the numerator and simplify the denominator.

tan(105)=(4+2√(,3))/(−2)

8. Divide each term in the numerator by −2

tan(105)=−2−√(,3)

Final Answer

tan(105)=−2−√(,3)

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