To find the missing side of a triangle (marked with a
?), you need to know what kind of triangle it is and what other information you have. Since the image doesn’t give numbers or angles, we’ll explain the most common ways this is done in school math.
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Step-by-step reasoning:
1.
If it’s a right triangle (one angle = 90°):
- Use the
Pythagorean Theorem:
> \( a^2 + b^2 = c^2 \)
where \( c \) is the longest side (hypotenuse), and \( a \) and \( b \) are the other two sides.
- If you know two sides, plug them into the formula and solve for the missing one.
- Example: If \( a = 3 \), \( b = 4 \), then \( c = \sqrt{3^2 + 4^2} = \sqrt{9+16} = \sqrt{25} = 5 \).
2.
If it’s NOT a right triangle, but you know:
- Two sides and the included angle → use the
Law of Cosines.
- Two angles and any side → use the
Law of Sines.
- All three angles and one side → also use Law of Sines.
3.
If it’s an equilateral triangle (all sides equal):
- Then all sides are the same — if you know one side, the others are identical.
4.
If it’s an isosceles triangle (two sides equal):
- If you know which two sides are equal, and you’re given one of those, the other matching side is the same length.
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But wait — in your image, the triangle has sides labeled
a,
b, and
?. There are no numbers or angles shown. That means
this is likely a general concept question, not a calculation problem.
In many textbooks or lessons titled “Finding A Missing Side of a Triangle,” they expect you to recognize that:
> You can only find a missing side if you have enough information — like two sides of a right triangle, or two sides and an angle, etc.
Since no values are given,
the answer must be conceptual.
However — looking again at the labels: side
a, side
b, and the third side is marked
?. In standard triangle notation, if this were a right triangle with legs
a and
b, then the hypotenuse would be
?, and the formula would be:
> \( ? = \sqrt{a^2 + b^2} \)
That’s the most common case taught in middle/high school when just labeled like this.
Also note: the logo says “a★help” — possibly hinting that
a and
b are known, and you’re solving for the third side using Pythagoras.
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✔ So, assuming this is a
right triangle with legs
a and
b, and
? is the hypotenuse:
Final Answer:
\( \sqrt{a^2 + b^2} \)
Parent Tip: Review the logic above to help your child master the concept of triangle missing.
