How do you find the value of sin^(-1)(sin (cos^(-1) (sin (pi/12))))sin1(sin(cos1(sin(π12))))?

2 Answers
Jul 17, 2016

sin^-1(sin(cos^-1(sin(pi/12))))=5pi/12sin1(sin(cos1(sin(π12))))=5π12.

Explanation:

We will use the following Rules :

(R1) : sintheta=cos(pi/2-theta)(R1):sinθ=cos(π2θ)

(R2) : cos^-1(costheta)=theta, theta in [o,pi](R2):cos1(cosθ)=θ,θ[o,π]

(R3) : sin^-1(sintheta)=theta, theta in [-pi/2,pi/2](R3):sin1(sinθ)=θ,θ[π2,π2]

Let us note that, by

(R1), sin(pi/12)=cos(pi/2-pi/12)=cos(5pi/12)(R1),sin(π12)=cos(π2π12)=cos(5π12)

So, cos^-1(sin(pi/12))=cos^-1(cos(5pi/12))cos1(sin(π12))=cos1(cos(5π12)), where,

5pi/12 in [0,pi]5π12[0,π], so, using (R2)(R2), we get,

cos^-1(cos(5pi/12))=5pi/12cos1(cos(5π12))=5π12

Again, as 5pi/12 in [-pi/2,pi/2]5π12[π2,π2], by (R3)(R3), we have,

sin^-1(sin(5pi/12))=5pi/12sin1(sin(5π12))=5π12

Finally, sin^-1(sin(cos^-1(sin(pi/12))))=5pi/12sin1(sin(cos1(sin(π12))))=5π12.

Hope, this will be of Help! Enjoy Maths.!

Jul 17, 2016

(5pi)/12=75^o5π12=75o

Explanation:

Use sin a = cos (pi/2-a) and,sina=cos(π2a)and,

if y=f(x) , x = f^(-1)y, f f^(-1)y=y and f^(-1)yf(x)=xy=f(x),x=f1y,ff1y=yandf1yf(x)=x.

The given expression is

sin^(-1)sin cos^(-1)sin(pi/12)sin1sincos1sin(π12)

=sin^(-1)sin (cos^(-1)cos(pi/2-pi/12))=sin1sin(cos1cos(π2π12))

=sin^(-1)sin((5pi)/12)=sin1sin(5π12)

=(5pi)/12=5π12