How do you answer this question?

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2 Answers
May 1, 2018

DeltaADC is an isosceles right triangle

:.

angleADC = 45^@

angleACB = 60^@ because is it one of the 3 angles of an equilateral triangle.

:.

angleDCB = 90^@+60^@ = 150^@

Because angleBDC is opposite one of two equal sides of Delta BDC:

angleBDC = (180^@-angleDCB)/2

angleBDC = (180^@-150^@)/2

angleBDC = 15^@

angle ADB = angle ADC - angleBDC

angle ADB = 45^@ - 15^@

angle ADB = 30^@ Q.E.D.

May 1, 2018

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Explanation:

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