Question

now plzzzz answer...............

Answer 1

Hello Dear ! :) 
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As we know In a regular pentagon 
All angles = 108°

i.e.∠P =∠Q =∠R =∠S = ∠T = 108 °
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In quadrilateral PZST
∠ TPZ  +∠ PZS  + ∠ ZST  +  ∠ STP = 360°
1/2∠P  + ∠ PZS +  108      + 108      = 360°
54 + 216 + ∠ PZS                             = 360°
270 + ∠ PZS                                     = 360°
∠ PZS                                               = 360 - 270 = 90°
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Answer 2

In quadrilateral PZST
∠ TPZ +∠ PZS + ∠ ZST + ∠ STP = 360°
1/2∠P + ∠ PZS + 108 + 108 = 360°
54 + 216 + ∠ PZS = 360°
270 + ∠ PZS = 360°
∠ PZS = 360 - 270 = 90°