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# Short Inverse Trig question

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1 What is the value of arcsin(−1/2) in degrees?

2

What is the value of arccos(3√2) in radians?

I ACCIDENTALLY PUT 12 IT IS SUPPOSED TO BE -1/2 FOR THE FIRST QUESTION

Nov 30, 2018
edited by jjennylove  Nov 30, 2018
edited by jjennylove  Nov 30, 2018

#1
+19863
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Just use a calculator to find  (unless you know )

arcsin (-1/2) = -30 or  210 degrees

arc cos (sqrt2 *3) is invalid

Arccos(sqrt(3)/2)   is also 30 degrees which is pi/6 radians   ( or - pi/6 radians also)

Nov 30, 2018
edited by ElectricPavlov  Nov 30, 2018
edited by ElectricPavlov  Nov 30, 2018
edited by ElectricPavlov  Nov 30, 2018
#2
+106532
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For the first one...make sure your calculator  [ or our calculator] is set to "degree" mode!!

1.  First of all ...arcsin (-12)  doesn't exist

I think you mean   arcsin (-1/2)  = -30°   = [360 - 30 ]° =  330°  [ positive result ]

2. arccos(3√2).....I think you mean arccos (√3/ 2)...set your calculator to "radian" mode

Note.....that on the second one...if we want the exact result...set your calculator back to "degree" mode and evaluate arccos(3√2)  =   30°

To convert this to an exact result....use this

30° x    pi / 180° =   (30/180) pi  = pi/6   (rads)

Nov 30, 2018
edited by CPhill  Nov 30, 2018
edited by CPhill  Nov 30, 2018
edited by CPhill  Nov 30, 2018