Question

Question: The lengths of the diagonals of a rhombus are 5 inches and 8 inches. What are the interior angle measures of the rhombus?

How you must answer:

- Sketch - draw the sketch:
- Known:
-Unknown:
-Rationale:
-Exquation and expression:


Steps:
- Include a sketch
-State the Known
-State the Unkown and represent with a variable
-Provide a rationale
-Include the equation, exact answer, and decimal approximation

Answer 1

The interior angles are approximately 64.02 degrees and approximately 115.98 degrees

The drawing is below.

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Step-by-step explanation:

A rhombus always has perpendicular diagonals. The two diagonals form four identical (aka congruent) right triangles as the figure shows below.

Notice how I've marked x and y as the unknown acute angle measures. Also, the two diagonals divide each other in half. The 8 splits into 4+4 and the 5 splits into 2.5+2.5

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Focus on one of the right triangles (they're all identical so it doesn't matter which you go for). We can use the tangent ratio to help determine the value of x.

`\tan(\text{angle}) = \frac{\text{opposite}}{\text{adjacent}}\\\\\tan(\text{x}) = (2.5)/(4)\\\\\tan(\text{x}) = 0.625\\\\\text{x} = \tan^(-1)(0.625)\\\\\text{x} \approx 32.005383^(\circ)\\\\\text{x} \approx 32.01^(\circ)\\\\`

Angle x is roughly 32.01 degrees.

Make sure your calculator is in degree mode.

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Similar steps can be done to find the value of y.

`\tan(\text{angle}) = \frac{\text{opposite}}{\text{adjacent}}\\\\\tan(\text{y}) = (4)/(2.5)\\\\\tan(\text{y}) = 1.6\\\\\text{y} = \tan^(-1)(1.6)\\\\\text{y} \approx 57.994617^(\circ)\\\\\text{y} \approx 57.99^(\circ)\\\\`

Or you could use the value of x to compute y like this

x+y = 90

y = 90 - x

y = 90 - 32.005383

y = 57.994617

y = 57.99

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Once we figure out x and y, it's simply a matter of doubling those values to get the interior angles of the rhombus. This is because we have the x angles next to each other to form two of the interior angles. So we have x+x = 2x = 2*32.01 = 64.02 degrees as one interior angle of the rhombus. The value is approximate.

The other interior angle is roughly y+y = 2y = 2*57.99 = 115.98 degrees

Notice how 2x+2y = 64.02+115.98 = 180

For any rhombus, the adjacent angles are supplementary (they add to 180 degrees).