Question

(5-cosecB) (2 cosecB +4)​

Answer 1

Correct options are A) , B) , C) and D)

secA=

8

17

⇒cosA=

17

8

⇒sinA=±

17

15

cscB=

4

5

⇒sinB=

5

4

⇒cosB=±

5

3

Now cos(A+B)=cosAcosB−sinAsinB

⇒cos(A+B)=

17

8

.

4

5

−(±

17

15

.±

5

3

)=±

85

36

or ±

85

84

∴sec(A+B)=±

36

85

,±

84

85