pls help btw yall are amazing for answering

a. (tan900°+sec135°) / csc(-90°)

tan 900  =   tan 180   =   0

sec 135  =  - sec 45  =  - 2/ √2  =   - √2

csc (-90)  =  csc (270)  =  -1 

So...this just evaluates  to    ( 0  - √2)  / 1   =  -√2

b. (cos 5π/4)(tan7π/4) / cot (π/2)

cos 5pi/4  = cos   225°  =  -√2/2

tan 7pi/4  =  tan 315°  =  -tan 45°  =  -1

cot pi/2  =  cot 90°   =  0

So......since we can't divide by  0....this is undefined