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Question
In the given figure, AC = 13cm, BC = 12 cm and ∠B = 90°. Without using tables, find the values of: sin A cos A
Solution
ΔABC is a right-angled triangle.
∴ AC2 = AB2 + BC2
⇒ AB2
= AC2 - BC2
= 132 - 122
= 169 - 144
= 25
⇒ AB = 5cm
sin A = `"BC"/"AC" = (12)/(13)`
cos A = `"AB"/"AC" = (5)/(13)`
sin A cos A
= `(12)/(13) xx (5)/(13)`
= `(60)/(169)`.
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