I study in class 9 i am having doubt inchap 8 , ques 4... At the last

This question was asked in Ex 8.1, 4

I study in class 9 i am having doubt in chap 8 , ques 4 ... At the last of this ques you have given only the value of angle OAB as 90°. But we have to give the value of 90° for all the angles and the .. ANGLES ARE AOB , BOC , COD , AOD AS 90°