Hello from MrBillDoesMath!
Answer:
See below
Discussion:
Triangles BAD and BCD are congruent by the SAS postulate.
* Side AD = DC because BD is the perpendicular bisector of AC.
* Angle ADB and CDB are both right angles, and hence equal, because
BD is the perpendicular bisector of AC)
Corresponding parts of congruent triangles are equal so angle BAD = angle BCD, which was to be proven.
Regards,
MrB
Answer:
total pages = 20
Step-by-step explanation:
60% of an unknown number is 12
Let the unknown number (total pages) be x.
60/100 of x = 12
60/100 * x = 12
3/5 x = 12
x = 12 * 5/3
x = 20
1. Check the drawing of the rhombus ABCD in the picture attached.
2. m(CDA)=60°, and AC and BD be the diagonals and let their intersection point be O.
3. The diagonals:
i) bisect the angles so m(ODC)=60°/2=30°
ii) are perpendicular to each other, so m(DOC)=90°
4. In a right triangle, the length of the side opposite to the 30° angle is half of the hypothenuse, so OC=3 in.
5. By the pythagorean theorem,

6. The 4 triangles formed by the diagonal are congruent, so the area of the rhombus ABCD = 4 Area (triangle DOC)=4*

=

(

)
Answer:
y = -1
Step-by-step explanation:
A horizontal line is of the form
y =
The y coordinate of the point (-2,-1) is -1
The equation is y = -1
First let’s express the total number of marbles as such:
y(yellow marbles) + r(red marbles)=23; y+r=23
now let’s express the relation of yellow marbles to red marbles:
y=2r(2 times red marbles) - 4(4 less marbles); y=2r-4
since we figured out what y equals, we can plug into the first equation we created:
(2r-4)+r=23
now solve for r:
2r-4+r=23
combine like terms
3r-4=23
add 4 to both sides
3r=27
divide both side by 3
r=9
plug r back into first equation and solve for y:
y+9=23
subtract 9
y=14
there are 9 red marbles and 14 yellow marbles!