Calculate the value of X.
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Calculate the value of X.
Let's remember that the sum of angles in a triangle is equal to 180.
Therefore, we will use the following formula:
We'll substitute the known data:
We'll combine similar terms:
We'll move terms to one side and maintain the appropriate sign:
We'll divide both sides by 9:
5
Can a triangle have a right angle?
This is a fundamental geometric rule! No matter what shape or size triangle you have, the three interior angles will always add up to exactly 180°. It's like a mathematical law of triangles.
Think of it like this: 8x means 8 × x and x means 1 × x. So 8x + x = (8 + 1)x = 9x. Always add the coefficients (numbers in front) when combining like terms.
That's completely normal! Not all triangle problems have whole number solutions. Just make sure your final angles still add up to exactly 180° when you substitute back.
No, you need the equation! Since you have unknown expressions (8x and 20+x), you must use the triangle angle sum rule: 115 + 8x + (20+x) = 180 to find x.
Look at the diagram carefully! The expressions 8x and 20+x are labeled next to their respective angles. The 115° is clearly marked at the top angle of the triangle.
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