Which is the closest to the area that is painted blue? A 308 units B. 116 units C. 463 units? D 124 units

Mathematics

1 answer:

Charra [1.4K]1 year ago

6 0

Step-by-step explanation:

first of all, all answer options are basically wrong, because an area is always measured in units² (and not just in units).

the blue colored area is the area of the whole square minus the area of the circle.

the side length of the square is 2 times the radius of the circle (the diameter) : 2×12 = 24 units.

so, the area of the square is

24² = 576 units²

the are of the circle is

pi×r² = pi×12² = 144pi units²

so, the blue area is

576 - 144pi = 123.6106579... ≈ 124 units²

therefore, D is the right answer.

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Answer the Blanks:

vfiekz [6]

Answer:

1. 90°

2. 90°

3. 40°

4. 45°

5. 45°

Step-by-step explanation:

Given: ΔABC,

CD⊥AB,

m∠A=50°,

m∠ACB=85°

Solution:

1. ∠ADC is a right ange, because CD⊥AB, so

$m\angle ADC=90^{\circ}$

2. ∠CDB is a right ange, because CD⊥AB, so

$m\angle CDB=90^{\circ}$

3. Consider triangle ACD. The sum of the measures of all interior angles is always 180°, so

$m\angle A+m\angle ADC+m\angle ACD=180^{\circ}\\ \\50^{\circ}+90^{\circ}+m\angle ACD=180^{\circ}\\ \\m\angle ACD=180^{\circ}-50^{\circ}-90^{\circ}=40^{\circ}$

4. By Angle Addition Postulate,

$m\angle ACD+m\angle BCD=m\angle ACB\\ \\40^{\circ}+m\angle BCD=85^{\circ}\\ \\m\angle BCD=85^{\circ}-40^{\circ}=45^{\circ}$

5. Consider triangle ABC. The sum of the measures of all interior angles is always 180°, so

$m\angle A+m\angle ACB+m\angle B=180^{\circ}\\ \\50^{\circ}+85^{\circ}+m\angle B=180^{\circ}\\ \\m\angle B=180^{\circ}-50^{\circ}-85^{\circ}=45^{\circ}$