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JAMB UTME - Mathematics - 2022

Question 1 Report

If \( \sin \theta = -\frac{3}{5} \) and \( \theta \) lies in the third quadrant, find \( \cos \theta \)

Answer Details

Where sin θ = opphyp → 
− 3 5

opp = -3, hyp = 5

using pythagoras formula 

hyp2 2  = adj2 2  + opp2 2

adj2 2  = hyp2 2  - opp2 2

adj2 2  = 52 2  - 32 2  → 25 - 9

adj2 2  = 16

adj = 4

cos θ = adjhyp → 
4 5

In third quadrant: cos θ is negative → - 45