In the right angled triangle shown below, if AB=3cm, BC=4cm then what is the value of cosA?
[2 Marks]
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Solution
Since ABC is a right angled triangle, we can apply Pythagoras theorem to get the length of side AC (hypotenuse).
Therefore, AC2=AB2+BC2 ⇒AC2=32+42 ⇒AC2 = 9 + 16 = 25 ⇒AC=√25=5 ⇒AC=5
[1 Mark]