Answer:
3
Step-by-step explanation:
There would be 12 people at the party!
In general, with n+1 people, the number of handshakes is the sum of the first n consecutive numbers: 1+2+3+ ... + n.
Since this sum is n(n+1)/2, we need to solve the equation n(n+1)/2 = 66.
This is the quadratic equation n2+ n -132 = 0. Solving for n, we obtain 11 as the answer and deduce that there were 12 people at the party.
Since 66 is a relatively small number, you can also solve this problem with a hand calculator. Add 1 + 2 = + 3 = +... etc. until the total is 66. The last number that you entered (11) is n.
Hope this helps!
Answer:
x =27
Step-by-step explanation:
3x - 4y=65
lets substitute the value of y in the equation:
3x -4(4) =65
3x = 65 +16
3x= 81
x= 81/3
x = 27
Answer:
∠Q = 53.13 degrees
Step-by-step explanation:
Given that ∆PQR, ∠P = 90degrees , this means that the triangle is a right angled triangle
Hence using the notation
SOH CAH TOA
where S is sine, C is cosine, T is tangent and O, A and H represents the size of the opposite, adjacent and hypotenuse sides
Considering ∠Q and the given sides
PR=16cm is the opposite side,
PQ= 12 cm is the adjacent side hence we use TOA
Tan Q = 16/12 =
Q = Arc tan 16/12
= 53.13 degrees
Answer:
7. 49
8. 10.4
Step-by-step explanation:
7) our hypotenuse is 8, and the side opposite the base of ladder and ground angle is 6, therefore we can use Sin
sin = opposite/hypotenuse
sin(x) = 6/8 = 3/4
sin-1(3/4) = 49
8) using the theorem that alternate exterior angles are congruent
the angle opposite side x is 30
tan = opposite/adjacent
tan(30) = x/18
x = 18tan(30) = 6√(3) = 10.4
you can also use 30-60-90 special right triangles.
the side opposite 30 is x
side opposite 60 is x√(3)
and side opposite 90 is 2x
