Work out the size of angle u.

There is a triangle with angles 75°, 65°, and u. The diagram is not to scale.

To find the size of angle u in a triangle, we need to use the fact that the sum of the interior angles in a triangle is always 18 0 ∘ . This is a basic property of triangles.
Given that the triangle has angles 7 5 ∘ , 6 5 ∘ , and u , we can set up the following equation:
7 5 ∘ + 6 5 ∘ + u = 18 0 ∘
First, let's add the known angles:
75 + 65 = 140
So, the equation becomes:
14 0 ∘ + u = 18 0 ∘
Next, we solve for u by subtracting 14 0 ∘ from both sides of the equation:
u = 18 0 ∘ − 14 0 ∘
u = 4 0 ∘
Therefore, the size of angle u is 4 0 ∘ .

Answered by DanielJosephParker | 2025-07-06