May someone please help me out? Please show full steps ♡´･ᴗ･`♡

Step-by-step 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

answer: cos [   arcsin (3/5) - arccos (1/2) ] =

step-by-step explanation: × = 3/5 = 0.6--> x = 36.87 and x = 180 - 36.87 = 143.13 deg

cos y = 1/2 --> y = +- 60 deg a. cos (x - y) = cos (143.13 - 60) = cos 83,13  

=

0.12

b. cos (36.87 - 60) = cos (-23.23) = 0.92

its very big question plz make it small