Answer:
4
Step-by-step explanation:
(sinx)^2 = 1 when cosx is 0 at pi/2 and 3pi/2
cosx = 1 when sinx is 0 at 0
therefore, A
Answer:
The discriminant of the quadratic equation is -7.
Step-by-step explanation:
We are given the following quadratic equation in the question:

Comparing to general quadratic equation:

We have to find the discriminant of the quadratic equation.
Formula:

Putting values, we get,

Thus, the discriminant of the quadratic equation is -7.
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!