Find the EXACT value of
sin(A−B) if cos A = 3/5 where A is in Quadrant IV and cos B = 12/13
where B is in Quadrant IV. Assume all angles are measured from standard position.

Respuesta :

Answer:

[tex]sin(A-B)= -\frac{33}{65}[/tex]

Step-by-step explanation:

step 1

Find the value of sin(A)

we know that

[tex]sin^2(A)+cos^2(A)=1[/tex]

we have

[tex]cos(A)=\frac{3}{5}[/tex]

substitute

[tex]sin^2(A)+(\frac{3}{5})^2=1[/tex]

[tex]sin^2(A)+\frac{9}{25}=1[/tex]

[tex]sin^2(A)=1-\frac{9}{25}[/tex]

[tex]sin^2(A)=\frac{16}{25}[/tex]

[tex]sin(A)=\pm\frac{4}{5}[/tex]

Remember that the angle A is in Quadrant IV

so

The value of sin(A) is negative

therefore

[tex]sin(A)=-\frac{4}{5}[/tex]

step 2

Find the value of sin(B)

we know that

[tex]sin^2(A)+cos^2(A)=1[/tex]

we have

[tex]cos(B)=\frac{12}{13}[/tex]

substitute

[tex]sin^2(B)+(\frac{12}{13})^2=1[/tex]

[tex]sin^2(B)+\frac{144}{169}=1[/tex]

[tex]sin^2(B)=1-\frac{144}{169}[/tex]

[tex]sin^2(B)=\frac{25}{169}[/tex]

[tex]sin(B)=\pm\frac{5}{13}[/tex]

Remember that the angle B is in Quadrant IV

so

The value of sin(B) is negative

therefore

[tex]sin(B)=-\frac{5}{13}[/tex]

step 3

Find the value of sin(A-B)

we know that

[tex]sin(A-B)= sinAcosB-cosAsinB[/tex]

substitute the given values

[tex]sin(A-B)= (-\frac{4}{5})(\frac{12}{13})-(\frac{3}{5})(-\frac{5}{13})[/tex]

[tex]sin(A-B)= (-\frac{48}{65})+(\frac{15}{65})[/tex]

[tex]sin(A-B)= -\frac{33}{65}[/tex]