Angles A, B and C of the inscribed quadrilateral ABCD are 2: 3: 4. Find Angle D.

Since the quadrilateral is inscribed in a circle, it is convex. The sum of the opposite angles of a convex quadrilateral is 180.

A + C = 180.

B + D = 180.

Let’s take one part of the ratio of the angles as X, then A = 2 * X, B = 3 * X, C = 4 * X.

2 * X + 4 * X = 180.

X = 180/6 = 30.

Then:

3 * 30 + D = 180.

D = 180 – 90 = 90.

Answer: Angle D = 90.



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