Answer: Choice A) Triangle ABC is similar to triangle ACD by AA
AA stands for Angle Angle. Specifically it means we need 2 pairs of congruent angles between the two triangles in order to prove the triangles similar. Your book might write "AA similarity" instead of simply "AA".
For triangles ABC and ACD, we have the first pair of angles being A = A (angle A shows up twice each in the first slot). The second pair of congruent angles would be the right angles for triangle ABC and ACD, which are angles C and D respectively.
We can't use AAS because we don't know any information about the sides of the triangle.
Answer:
Bc=20
Step-by-step explanation:
Sin61=BC/AC=BC/23
BC=23sin61=20
First, make up some variables to represent the number of Girls and Boys in the choir.
B = number of boys
G = number of girls
You know that there are 4 times as many girls in the choir as boys. Therefore, the equation you can write is:

If you cross-multiply, then you get the simplified equation:
G = 4B
Intuitively this makes sense since if you multiplied the number of boys in the class by 4, that would be equal to the number of girls you have.
Now, we know that the total class size is 60. So girls plus boys equals 60:
G+B = 60
To solve the equation, replace the G in this equation with the replacement you found before, 4B.
G + B = 60 -->
4B + B = 60 -->
5B = 60 -->
B = 12
However, you are trying to find the number of girls, so plug the answer back into your equation.
G + B = 60 -->
G + 12 = 60 -->
G + 12 -12 = 60 - 12 -->
G = 48
The number of girls you have is 48.
<u>Answer-</u> Length of the curve of intersection is 13.5191 sq.units
<u>Solution-</u>
As the equation of the cylinder is in rectangular for, so we have to convert it into parametric form with
x = cos t, y = 2 sin t (∵ 4x² + y² = 4 ⇒ 4cos²t + 4sin²t = 4, then it will satisfy the equation)
Then, substituting these values in the plane equation to get the z parameter,
cos t + 2sin t + z = 2
⇒ z = 2 - cos t - 2sin t
∴ 


As it is a full revolution around the original cylinder is from 0 to 2π, so we have to integrate from 0 to 2π
∴ Arc length



Now evaluating the integral using calculator,

The number of permutations of 8 people taken 6 at a time is given by: