Question #d6fb5

1 Answer
Dec 4, 2015

See explanation.

Explanation:

[1]" "=csc(pi/12)

Reciprocal Identity: csctheta=1/sintheta

[2]" "=1/sin(pi/12)

Represent pi/12 as a difference of two special angles.

[3]" "=1/sin((3pi)/12-(2pi)/12)

[4]" "=1/sin(pi/4-pi/6)

Difference Identity: sin(alpha-beta)=sinalphacosbeta-cosalphasinbeta

[5]" "=1/(sin(pi/4)cos(pi/6)-cos(pi/4)sin(pi/6))

You can solve these since pi/4 and pi/6 are special angles.

[6]" "=1/((sqrt2/2)(sqrt3/2)-(sqrt2/2)(1/2))

[7]" "=1/((sqrt6/4)-(sqrt2/4))

[8]" "=1/((sqrt6-sqrt2)/4)*4/4

[9]" "=4/(sqrt6-sqrt2)

Rationalize the denominator.

[10]" "=4/(sqrt6-sqrt2)*(sqrt6+sqrt2)/(sqrt6+sqrt2)

[11]" "=(4(sqrt6+sqrt2))/(6-2)

[12]" "=(cancel4(sqrt6+sqrt2))/cancel(4)

[13]" "=color(blue)(sqrt6+sqrt2)