Question

Please help me asap!

Answer 1

7. Law of cosines

a² = b² + c² - 2bc cos A

where a is the side opposite to ∠A and b and c are adjacent sides to ∠A.

Here, a=BC= 3.8

b=CA =4.8

c = AB = 3.2

Substituting the values in the formula,

3.8² = 4.8² + 3.2² - 2(4.8)(3.2) cos A

30.72 cos A =23.04 + 10.24 -14.44=18.84

cos A = 18.84/30.72 = 0.6133

∴ cos A =0.6133

8. It is a right angled triangle.

Pythagoras theorem

hypotenuse² = Perpendicular² + base²

Here, hypotenuse = 6.7, base = 5.4

Perpendicular² = 6.7² -5.4²=44.89 - 29.16 =15.73

Perpendicular = √15.73 = 3.966 = 3.97

∴ The length of the missing side is 3.97.

9. Given:   Side of new cube = 5 * Side of original cube

Let the side of the original cube measure 1 unit.

So, volume of original cube = side³ = 1

The side of new cube = 5 * 1 =5 units

So, volume of new cube = side³ = 5³ =125

The volume of the bigger cube is 125 times larger than the original cube.

10. Given : Height of the cone = 7 in

Radius of the base of the cone = 2 in

Volume of cone = (1/3) πr²h

                           =(1/3)π(2²)(7)

                           =29.32 cubic inches

∴ Volume of the cone is 29.32 cubic inches.

11. The given equation is:

x² -18x +10 =0

(x² -18x + 9²) +10 -9² =0

(x-9)²-71 =0

(x-9)² =71

x-9 =√71

x = 9 + √71

∴ x = 9+√71