A convex quadrilateral $ABCD$ is given in which $\angle DAB = \angle ABC = 45^o$ and $DA = 3$, $AB = 7\sqrt2$, $BC = 4$. Calculate the length of side $CD$.
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Tags: geometry, angles
Hellboy1234
07.04.2021 08:27
this sum is very easy.......and can be done by applying cosine rule for 3 times.......(trigonometric approach) i get the answer as DC
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RedFireTruck
07.04.2021 15:37
Hellboy1234 wrote: this sum is very easy.......and can be done by applying cosine rule for 3 times.......(trigonometric approach) i get the answer as DC i have a nicer solution. extend $AD$ and $BC$ until they intersect at a point we will call $E$. $\angle D=90$, $DE=4$, and $CE=3$ so we have $3-4-5$ triangle so answer is $\boxed{5}$