triangle or trig problem?

Question

I always thought a 3,4,5 triangle had angles of 30 60 and 90 deg
If so then the sin of 30 is not 1/2 but 4/5..huh..?

Answer 1

The sin of 30 deg is 1/2, and the sin of 60 deg is (sqrt of 3)/2
a 3-4-5 triangle is not a 30-60-90 triangle. In a 30-60-90 triangle, the side lengths are always as follows:
shortest leg length=x
longest leg length=x(sqrt of 3)
hypotenuse length=2x

Answer 2

No, a 3-4-5 triangle does not have 30°-60°-90° angles.
The angles are approximately 37°-53°-90°.

Note that sin(37°) = 3/5, not 4/5. The smallest angle is opposite the smallest side.

Answer 3

Incorrect thought. A 3-4-5 has the 90, but NOT the 30-60 angles.

Answer 4

no
you're mixing up the Pythagorean theorem with the special right triangles

a special right triangle will have 30, 60, 90 and the sides will correspond with 1, square root of 3, and 2

3,4,5 are pythagorean triples that fit into the theorem exactly

Answer 5

No. That is because, a unit circle is used in trigonometry. That is, the radius is 1. Thus, the triangle 3, 4, 5 does not apply in your contention. *winks*

Answer 6

without dividing into 2 top angles triangles: utilising cosine rule to locate area EF: EF^2= DF^2 + DE^2 - 2(DF)(DE)cos(f) EF^2= 132 + 1600 - 2(eleven)(40)cos(12) EF^2 = 871.23 EF = sqrt(871.23) EF = 29.52cm Now utilising Sine rule to locate perspective E: e/sinF = d/sinE 40/sin12=29.fifty 2/sinE 192.39 = 29.fifty 2/sinE sinE192.39 = 29.fifty 2 sinE = 0.153 E = sin^-a million(0.153) E= 8.8 for this reason D= one hundred and eighty - (12 + 8.8) = one hundred and eighty - (20.8) = 159.2 Sorry in case you had to divide into top perspective triangles... i have not achieved this in a lengthy time period so i'm somewhat fuzzy, yet i imagine it truly is meant to be proper... desire it truly is...