In parallelogram ABCD, EC is perpendicular DC, angle B is congruent to angle E and angle A = 100 degrees. Find angle CDE?
MY WORK: d = degrees
Since angle A = 100d, I subtracted 100d from 180d to find angel D = 80d.
Angle D MUST = angle B because corners of parallelograms are equal.
Angle B = angle E = 80d.
I also know that EC is perpendicular to DC. Perpendicular told me that angle C must be 90d, right? Well, if this is true, then angle CDE must = angle C - Angle E.
Thus, angle CDE = 10d.
My answer is 10d.
Book's answer is 20d.
What did I do wrong?
Is my thinking okay here?
MY WORK: d = degrees
Since angle A = 100d, I subtracted 100d from 180d to find angel D = 80d.
Angle D MUST = angle B because corners of parallelograms are equal.
Angle B = angle E = 80d.
I also know that EC is perpendicular to DC. Perpendicular told me that angle C must be 90d, right? Well, if this is true, then angle CDE must = angle C - Angle E.
Thus, angle CDE = 10d.
My answer is 10d.
Book's answer is 20d.
What did I do wrong?
Is my thinking okay here?