Question-146776

Question Number 146776 by mathdanisur last updated on 15/Jul/21

Commented by mr W last updated on 15/Jul/21

{A B}^{2} = 20^{2} - x^{2} = {(20 + 5)}^{2} + 10^{2} - 2 \times 25 \times 10 \cos C

{A D}^{2} = x^{2} = 5^{2} + 10^{2} - 2 \times 5 \times 10 \cos C

\Rightarrow 20^{2} - x^{2} = {(20 + 5)}^{2} + 10^{2} + 5 (x^{2} - 5^{2} - 10^{2})

\Rightarrow x^{2} = 50

\Rightarrow x = 5 \sqrt{2}

Commented by mathdanisur last updated on 15/Jul/21

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