Mathematics
tk22
19

If cos θ = -2/5 and tan θ > 0, what is the value of sin θ? PLEASE HELP!!!

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bbb911

if cosФ<0 and tg Ф>0; then we are in the third quadrant, then sin Ф<0 Fundamental realtion of trygonometry: sin²Ф+cos²Ф=1 Then: sin Ф=⁺₋√(1-cos₂Ф): Because we are in the third quadrant; sin Ф=-√(1-cos²Ф) Sin Ф=-√(1-(-2/5)²)=-√(1- 4/25)=-√(21/25)=-√21 / 5 Answer: sin Ф=-√21 / 5

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