In quadrilateral ABCDABCD, △A\triangle A is a right angle, AB=53AB=\dfrac{5}{3}, BC=8BC=8, CD=6CD=6, and AD=5AD=5. Are points A,B,C,DA, B, C, D concyclic?

Answer: No, the points A,B,C,DA, B, C, D are not concyclic.

Step-by-step solution

Step 1: Draw the quadrilateral and diagonal

First, let's visualize the quadrilateral ABCDABCD. We are given that ∠A\angle A is a right angle. This means that △ABD\triangle ABD is a right-angled triangle. We can use the Pythagorean theorem to find the length of the diagonal BDBD.

Step 2: Calculate the length of diagonal BD

Substitute the given lengths of AB=53AB = \frac{5}{3} and AD=5AD = 5 into the Pythagorean theorem. Calculate BD2BD^2 and then take the square root to find the length of BDBD.

Step 3: Check if triangle BCD is a right-angled triangle

For points A,B,C,DA, B, C, D to be concyclic, the quadrilateral must be cyclic. A property of cyclic quadrilaterals is that the sum of opposite angles is 180∘180^\circ. Since ∠A=90∘\angle A = 90^\circ, if the quadrilateral is cyclic, then ∠C\angle C must also be 90∘90^\circ. Let's check if △BCD\triangle BCD is a right-angled triangle using the Pythagorean theorem. If BC2+CD2=BD2BC^2 + CD^2 = BD^2, then ∠C=90∘\angle C = 90^\circ.

Step 4: Compare the squares of the sides

We compare the sum of the squares of sides BCBC and CDCD with the square of the diagonal BDBD. We found BC2+CD2=100BC^2 + CD^2 = 100 and BD2=2509BD^2 = \frac{250}{9}.

Step 5: Conclusion

Since BC2+CD2≠BD2BC^2 + CD^2 \neq BD^2, △BCD\triangle BCD is not a right-angled triangle, and therefore ∠C≠90∘\angle C \neq 90^\circ. Since the sum of opposite angles ∠A+∠C≠180∘\angle A + \angle C \neq 180^\circ, the quadrilateral ABCDABCD is not cyclic. Thus, points A,B,C,DA, B, C, D are not concyclic.

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