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Need help with finding the value of expressions.

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Need help with finding the value of expressions.

Feb 19, 2018

#1
+18329
+2

1.  remember   cos^2 + sin^2 = 1

sin^2 = 1- cos^2

sin = sqrt (15/16)       (we are only concerned about the POSITIVE root in the 1st quadrant)

tan = sin/cos       sqrt(15/16) / 1/4   = 4 sqrt(15/16)   = 3.873

2.  sin (theta - pi/2)    results in shifting the sin wave pi/2 to the right which is an inverted cos wave

so sin (theta-pi/2)    is   - cos(theta) =  - .54

Feb 19, 2018
edited by ElectricPavlov  Feb 19, 2018

#1
+18329
+2

1.  remember   cos^2 + sin^2 = 1

sin^2 = 1- cos^2

sin = sqrt (15/16)       (we are only concerned about the POSITIVE root in the 1st quadrant)

tan = sin/cos       sqrt(15/16) / 1/4   = 4 sqrt(15/16)   = 3.873

2.  sin (theta - pi/2)    results in shifting the sin wave pi/2 to the right which is an inverted cos wave

so sin (theta-pi/2)    is   - cos(theta) =  - .54

ElectricPavlov Feb 19, 2018
edited by ElectricPavlov  Feb 19, 2018