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triangle ABD is a equilateral triangle.

so each angle is 60°

<ADB=60°

<BAD=60°

again

we have

CD is perpendicular to AD[tangent on the arc is perpendicular to the radius]

:. ADC=90°

°

again

In triangle ADC

<A+<B+<C=180°[sum of a interior angle of a traingle is 180°]

60°+90°+x=180°

x=180°-150°

x=30°

is a right answer.

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

answer:

what is your question that you ask

step-by-step explanation: