Please helpsina×tga=1/2find cosa
1 answer:
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Answer:
Step-by-step explanation:
Adjacent angles of parallelogram are supplementary.
∠A + ∠D = 180
Divide both sides by 2
∠A +
∠D = 90
∠PAD + ∠ADP = 90 --------------------(I)
IN ΔPAD,
∠PAD + ∠ADP + ∠APD = 180 {angle sum property of triangle}
90 + ∠APD = 180 {from (I)}
∠APD = 180 - 90
∠APD = 90
∠SPQ = ∠APD {vertically opposite angles}
∠SPQ = 90°
Similarly, we can prove ∠PQR = 90° ; ∠QRS = 90° and ∠RSP = 90°
In a quadrilateral if each angle is 90°, then it is a rectangle.
PQRS is a rectangle.