Small Question

[John]

I have been asked to Solve graphically sin3x = 0.2 (0≤x≤180)

I can plot the graph of it fine and can get the answer using a calculator easily enough but i dont understand how to get the answer by solving it graphically as the question asks?

[John]

Sorry about this but there are 3 others which i have to solve graphically i found which are

3cos2x=0.65 (-180≤x≤180) Answer = -2.47, -0.68, 0.68, 2.47
2tan t° -3 = 0 0≤t≤720) Answer = 56.3, 236.3 , 416.3 , 596.3
0.3cos x/6 +0.14 = 0 (-180≤x≤360) Answer = No Solutions

I dont have a clue who to get to those answer at all

Sorry to keeping asking you question but im really lost on this bit.

[Unregistered]

3cos2x=0.65 (-180≤x≤180) Answer = -2.47, -0.68, 0.68, 2.47
2tan t° -3 = 0 0≤t≤720) Answer = 56.3, 236.3 , 416.3 , 596.3
0.3cos x/6 +0.14 = 0 (-180≤x≤360) Answer = No Solutions

1)

3cos2x=0.65

cos2x=0.65 / 3

2x= inv cos (0.65 / 3)

2x = inv cos (0.21666...) your answers appear to be in radians, so switch to radians mode.

2x = ±1.352 ... radians, 2pi ±1.352 ... radians [ any cos graph repeats every 2pi units]


x= ±0.6761..., ±2.47....

2)

2tan t° -3 = 0

tan t° = 3/2

t° = inv tan (1.5) [ tan repeats every 180 degrees ]

t° = 56.30..., 56.30 + 180, 56.30 + 2(180), 56.30 +3(180)

t° = 56.30, 236.30..., 416.30..., 596.30...,


3)

0.3cos x/6 +0.14 = 0

cos x/6 = -0.14/0.3

cos x/6 = -0.466666....

x/6 = inv cos (-0.46666....)

x/6 = ±117.818..., 360±117.818

x= 6(±117.818..., 360±117.818)

x= no solutions in the range

[John]

Thx very much

[John]

For the first question you explained how do you convert to radian mode?

[john]

and sorry again but on the 3cos2x the last bit i dont understand how you get to. Sorry for being such a nuisance.