Answer:
Explanation:
METHOD 1
in centre it is split by 4, each angle is equal.
in a square angles add up to 360°
360/4=90°
∴∠DOC=90°
if you have to do more work or have toexplain more, or you dont get that way there is another method:
METHOD 2
since ABCD is a square it alladds up to 360°
so ∠A=B=C=D=90°
in triangle DOC anles add up to 180°
each diagonal cuts angleA,B,C and D in half
so in triangle DOC, ∠ODC=∠CDO=45
∠DOC=180-∠DOC-∠CDO (or 180-(∠DOC+∠CDO)
∠DOC=180-45-45
∠DOC=90