Question

pls solve it..
with explanation

Answer 1

Answer:

Perimeter of envelope = 15√2(√2 + 3)

Area of envelope = 1125/2 = 562.5 cm²

Area of square BDFE = 450 cm²

Step-by-step explanation:

In square ABCD , AB = 15 cm

AB = AD

BD² = AB² + AD²

⇒ BD² = AD² + AD²

⇒ BD² = 2AD²

⇒ BD² = 2(15)²

⇒ BD² = 2(225)

⇒ BD² = 450

⇒ BD = √450 = √2×225 = 15√2

Perimeter of envelope = AB + AD + BE + EF + DF

BD = BE = EF = DF

⇒ BE = EF = DF = 15√2 CM

Perimeter = 15 + 15 + 15√2 + 15√2 + 15√2

                 = 2(15) + 3(15√2)

                 = 30 + 45√2

                 = 15√2(√2 + 3) cm

Area of envelope = ar(ABD) + ar(BDEF)

ar(ABD) = 1/2 × 15 × 15 = 225/2

ar(BDEF) = (15√2)² = 225 × 2 = 450

⇒ Area = 225/2 + 450 = 1125/2 = 562.5 cm²

ar(BDEF) = (15√2)² = 225 × 2 = 450