Traditional Culture Encyclopedia - Traditional stories - As shown in the figure, quadrilateral paper ABCD, where ∠ B = 120 and ∠ D = 50. Now, its lower right corner is folded inward into △PCR,

As shown in the figure, quadrilateral paper ABCD, where ∠ B = 120 and ∠ D = 50. Now, its lower right corner is folded inward into △PCR,

∠C=95

Let the folded c angle be c',

Because CP//AB, ∠ CPC' = ∠ B = 120,

RC//AD，∠CRC'=∠D=50，

Because △PCR and △PC'r are symmetrical according to PR,

Then ∠ CPR = ∠ C' PR =1/2 * ∠ CPC' = 60;

∠CRP =∠C ' RP = 1/2 *∠CRC ' = 25；

De: ∠ c = 180-60-25 = 95。