Question

Given: sinA= -3/5 , 3pi/2 13 years ago

Answer 1

first calculate cos A

Answer 2

How would i do that? would it be -4/5?

Answer 3

can be either -4/5 or 4/5

Answer 4

but look at interval 3pi/2<A<2pi

Answer 5

so it is 4/5 because cos is positive in 4th qquadrant

Answer 6

yea. i see. then what would i do?

Answer 7

now sin 2A=2*sin A *cos A

Answer 8

so then tanB is negligible?

Answer 9

yep I dont understand why they are speaking of tan B at all .The qn asks for sin 2A which wee just worked out !

Answer 10

Thank You!

Answer 11

yw :)