Explanation: In right-angled triangles, the following trig function can be applied: sin θ = opposite / hypotenuse cos θ = adjacent / hypotenuse tan θ = opposite / adjacent
Now, for the given triangle: We want the functions including x and y. Let's check the relation between these variables and each angle in the triangle: 1- For angle D: x is the adjacent side y is the hypotenuse Based on the above rules: cos D = adjacent / hypotenuse cos D = x / y
2- For angle E: x is the opposite side y is the hypotenuse Based on the above rules: sin E = opposite / hypotenuse sin E = x / y
