Question

Find the least positive value of the angle A for which

(a) sin A = 0.2 and cos A is negative
(b)tan A = -.5 and sin A is negative
(c) cos A = sin A and both are negative
(d) sin A = -.02275 and A >360

I literally have no idea what to do . Can someone guide me please.

Answer 1

a) sine is positive, cosine is negative, you must be in quadrant II

Answer 2

in order to find that angle, take a calculator and find \(\sin^{-1}(0.2)\)
that is not the angle you are looking for, that will give you this one

Answer 3

to find the angle you want, find
\[\pi-\sin^{-1}(0.2)\] if you are working in degrees for some reason put your calculator in degree mode and find
\[180-\sin^{-1}(0.2)\]

Answer 4

so when i subtract 180 - sin(inverse ( 0.2) .. I will find the min angle ?
frankly, I dont get what angle they want

Answer 5

you want that angle

Answer 6

arcsine will not give you that one, arcsine only gives you an angle in quadrant 1 or 4, you want the one in quadrant 2, in other words the angle between 90 and 180

Answer 7

@satellite73 what about the last part part d when it says A>360 , what do they mean ? d

Answer 8

http://openstudy.com/updates/5404b92de4b0f2ed1e146373