Hello jamal

here is the first one 

cos (Arc sin 7/25)

Just write Arc sin 7/25 in terms of cosine

arc sin 7/25 = arc cos sqrt ( 1-(7/25 ) ²  )

= arc cos 24/25

now put this value in original question

cos (arc cos 24/25)

= 24/25 Answer

Just try other parts let me know in case of problem

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