Find the area of the quadrilateral ABCD in which ab=5cm, bc=4.5cm, cd=3.5cm, da=4cm and ac=6.5cm

A(ABCD) ≈ 17.285 cm²

Step-by-step explanation:

A = √s(s - a)(s - b)(s - c)

s = (a + b + c)/2

a ; b ; c = the sides of the triangle

s = (AB + BC + AC)/2 = (5cm + 4.5cm + 6.5cm)/2 = 16cm/2 = 8 cm

A(ABC) = √8(8 - 5)(8 - 4.5)(8 - 6.5)

= √8×3×3.5×1.5

= √126

≈ 11.225 cm²

     2. A(ACD) = √s(s - AC)(s - CD)(s - AD)

s = (AC + CD + AD)/2 = (6.5cm + 3.5cm + 4cm)/2 = 14cm/2 = 7 cm

A(ACD) = √7(7 - 6.5)(7 - 3.5)(7 - 4)

= √7×0.5×3.5×3

= √36.75

≈ 6.060 cm²

     3. A(ABCD) = 11.225cm² + 6.060cm² = 17.285 cm²

4.6875 pounds

step-by-step explanation:

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.