Well, that's the same thing as cosine of x. So as you can see, this red graph is the same thing as cosine of x. We know that from our trig identities, and you can also see it intuitively or graphically just by looking at these graphs. And what is cosine of x plus pi over two? Well, once again, from our trig identities, we know that that is the exact same thing as negative sine of x. So there you have it, the visual argument. Just start with this knowledge, shift both of these graphs to the left by pi over two.