Monday

September 22, 2014

September 22, 2014

Posted by **Anonymous** on Tuesday, October 19, 2010 at 11:28pm.

- trig -
**Reiny**, Tuesday, October 19, 2010 at 11:56pmgiven cos x = 4/5

by making a diagram, you should recognize the 3,4,5 right-angles triangle

secondly, the cosine is positive in quadrants I and IV

in I:

sinx = 3/5 , csc x = 5/3

cosx = 4/5 , sec x = 5/4

tanx = 4/3 , cot x = 3/4

you do IV

back to cos(pi over 2-x)=3/5

cos (π/2 - x) = 3/5

(cosπ/2)(cosx) + (sinπ/2)(sinx)= 3/5

sinx = 3/5

(hey, we knew that!)

**Answer this Question**

**Related Questions**

trig - If cos(t)=(-7/8) where pi<t<(3pi/2), find the values of the ...

TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...

trig - find the exact values of the six trig functions of the angle. -750 sin(-...

trig - how would you verify this trig identity (1+cos(x) / 1-cos(x)) - (1-cos(x...

Trig Help! - Question: Trying to find cos π/12, if cos π/6 = square ...

trig - find the 5 other trig functions if cos(theta) = square root of 2/2 and ...

trig 26 - simplify to a constant or trig func. 1. sec Ču-tan Ču/cos Čv+sin Čv ...

trig - If cos 0 = - 1/2 and tan 0 > 0, find the quadrant that contains the ...

Math - Solving Trig Equations - What am I doing wrong? Equation: sin2x = 2cos2x ...

Trig - Compute inverse functions to four significant digits. cos^2x=3-5cosx ...