A trig identity is <span>asinucosu=<span>a/2</span>sin(2u)</span>So you can write your equation as<span>y=sin(x)cos(x)=<span>1/2</span>sin(2x)</span>Use the crain rule here<span><span>y′</span>=<span>d/<span>dx</span></span><span>1/2</span>sin(2x)=<span>1/2</span>cos(2x)<span>d/<span>dx</span></span>2x=cos(2x)</span>The curve will have horizontal tangents when y' = 0.<span><span>y′</span>=0=cos(2x)</span>On the interval [-pi, pi], solution to that is<span><span>x=±<span>π4</span>,±<span><span>3π</span>4</span></span></span>
The answer is the 3rd choice. The beginning temperature is -9 so you add the 7 to the -9 degrees to find the temperature at noon because it increased.
Without seeing the graph, it's impossible to tell. The same can be said if we don't know the function rule. However, we can rule out three non-answers.
Choice B is false because the interval [1,3] has f(x) below zero but the rest of the interval to the right of x = 3 has f(x) not below zero.
Choice C is false. The value x = -1 leads to f(x) = 0 which is not greater than 0
Choice D is false because the values 8 and 4 are positive
After eliminating B, C, & D, we are left with choice A as the answer.
He can either measure the third side length, apply the Pythagorean theorem to find the height of the triangle, and then calculate the area, or he can find the measure of the included angle between the known side lengths and use trigonometry to express the height of the triangle and then determine the
area of the triangle
