# Question #2c9a8

##### 3 Answers

#### Explanation:

If

The ratio

Since

The sum formula for sine is:

#### Explanation:

Acute angles are smaller than

than 90°, but less than

it is on second quadrant. Base

Since

Perpendicular

#### Explanation:

#"using the "color(blue)"trigonometric identities"#

#•color(white)(x)sin^2x+cos^2x=1#

#rArrsinx=+-sqrt(1-cos^2x)#

#rArrcosx=+-sqrt(1-sin^2x)#

#•color(white)(x)sin(A+B)=sinAcosB+cosAsinB#

#"to obtain the expansion we require the values of"#

#cosA" and "sinB#

#"since A is obtuse then "cosA<0#

#rArrcosA=-sqrt(1-(3/5)^2)=-sqrt(16/25)=-4/5#

#"since B is acute then "sinB>0#

#rArrsinB=sqrt(1-(15/17)^2)=sqrt(64/289)=8/17#

#rArrsin(A+B)#

#=(3/5xx15/17)+(-4/5xx8/17)#

#=45/85-32/85#

#=13/85#