Grade 11 kept forces on one line: a push forward, a weight down. This year they point wherever they like, and the first skill of the course is taking one slanted arrow apart. A force is a vector: it has a magnitude $F$ in newtons — how hard — and a direction angle $\theta$ in degrees, measured from the horizontal $+x$ axis. Those two numbers say everything about it.

Take it apart and you get its two components, the shadows it casts on the axes: $F_x = F\cos\theta$ — read aloud F-x equals F cos theta — is the part lying along the horizontal, and $F_y = F\sin\theta$ — F-y equals F sin theta — is the part standing up the vertical. The subscript names the AXIS, not an order: $x$ is the horizontal shadow, $y$ the vertical one, and every symbol here is measured in newtons except $\theta$, which wears degrees.

Why cosine on $x$? Draw the right triangle. The angle sits between the arrow and the x-axis, so the x-side TOUCHES the angle — it is the adjacent side, and $\cos\theta = \dfrac{\text{adjacent}}{\text{hypotenuse}}$. The y-side sits across from the angle — opposite — and $\sin\theta = \dfrac{\text{opposite}}{\text{hypotenuse}}$. Learn it as touching-versus-across and it survives every rotated diagram the exam can print. The one caveat worth a mark: this holds when $\theta$ is measured from the x-axis. Give a problem an angle from the VERTICAL and the two swap — read the diagram, not the habit.