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Question
In ΔABC, if a = 18, b = 24, c = 30 then find the values of sinA.
Sum
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Solution
Given: a = 18, b = 24 and c = 30
`cos A = (b^2+c^2-a^2)/(2bc)`
`cos A = (24^2+30^2-18^2)/(2xx24xx30)`
= `(576+900-324)/1440`
= `1152/1440`
= `4/5`
`sin^2 A = 1-cos^2 A`
= `1 - (4/5)^2`
= `1- 16/25 = 9/25`
= `sinA = sqrt(9/25)`
= `3/5`
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