Legs of 3 and 4 cm meet at the right angle; the hypotenuse is 5 cm, the acute angles are 36.8699° and 53.1301°, and the triangle encloses 6 cm².
Right triangle, to scale
ਗਣਨਾ ਕਿਵੇਂ ਹੁੰਦੀ ਹੈ S
Hypotenuse (Pythagoras)
c=a2+b2=32+42=5cm
Angle α
α=arctanba=arctan43=36.869898∘
Area and perimeter
Area=21ab=21×3×4=6cm2,P=a+b+c=12cm
Height onto the hypotenuse, inradius, circumradius
h=cab=2.4cm,r=2a+b−c=1cm,R=2c=2.5cm
The circumcentre of a right triangle is the midpoint of its hypotenuse.
ਸਮਕੋਣ ਤਿਕੋਣ ਕੈਲਕੁਲੇਟਰ: ਕਰਣ, ਭੁਜਾਵਾਂ ਅਤੇ ਕੋਣ ਬਾਰੇ
A right triangle is fixed by any two of its parts as long as one of them is a side. With both legs known, Pythagoras' theorem gives the hypotenuse c = √(a² + b²). With a side and an acute angle, the rest follows from sin α = a/c, cos α = b/c and tan α = a/b, and the two acute angles always add up to 90°.
The default legs of 3 cm and 4 cm make the 3-4-5 triangle: hypotenuse 5 cm, area 6 cm², perimeter 12 cm and angles of 36.8699° and 53.1301°. Builders use that ratio to square a corner, since marks 3 m and 4 m from it along two walls should be exactly 5 m apart. The results also include the height onto the hypotenuse (ab/c), the inradius ((a + b − c)/2) and the circumradius (c/2).
Angle α is opposite leg a and β is opposite leg b. Angles can be typed in degrees, radians, gradians or turns and must lie strictly between 0° and 90°.
ਹੱਲ ਕੀਤੀਆਂ ਉਦਾਹਰਨਾਂ
Legs 3 and 4
I know
Both legs (a and b)
Leg a (opposite α)
3 cm
Leg b (opposite β)
4 cm
ਨਤੀਜੇ ਦੀ ਇਕਾਈ
ਸੈਂਟੀਮੀਟਰ (cm)
Hypotenuse c
5 cm
ਖੇਤਰਫਲ
6 cm²
Angle α
36.869898 °
Angle β
53.130102 °
Height onto the hypotenuse
2.4 cm
Inradius
1 cm
Circumradius
2.5 cm
ਘੇਰਾ
12 cm
ਜਾਂਚ ਦਾ ਸਰੋਤ: 3-4-5 triple; h = 3·4/5; r = (3 + 4 − 5)/2; Python 3.8 math: degrees(atan(3/4))
ਜਾਂਚ ਦਾ ਸਰੋਤ: Side opposite 30° is half the hypotenuse; Python 3.8 math: 10*cos(radians(30)), 25*sqrt(3)/2
45° angle gives equal legs (edge case)
I know
Leg a and angle α
Leg a (opposite α)
7 cm
Angle α
45 °
ਨਤੀਜੇ ਦੀ ਇਕਾਈ
ਸੈਂਟੀਮੀਟਰ (cm)
Leg b
7 cm
Hypotenuse c
9.899495 cm
ਖੇਤਰਫਲ
24.5 cm²
Angle β
45 °
ਜਾਂਚ ਦਾ ਸਰੋਤ: tan 45° = 1 so b = a; Python 3.8 math: 7*sqrt(2)
ਸਵਾਲ
How do you find the hypotenuse of a right triangle?
Square both legs, add them and take the square root: c = √(a² + b²). Legs of 3 and 4 give √25 = 5, and legs of 6 in and 8 in give 10 in. If you know one leg and the angle opposite it instead, divide by the sine: c = a / sin α, so a 5 cm leg opposite 30° means a 10 cm hypotenuse.
How do you find a missing side of a right triangle?
For a missing leg, subtract the squares: b = √(c² − a²). A hypotenuse of 13 and a leg of 5 give √(169 − 25) = 12. The hypotenuse must be longer than either leg, or no right triangle exists. With one side and an angle, use SOHCAHTOA: opposite = hypotenuse × sin α and adjacent = hypotenuse × cos α.
What are the side ratios of a 30-60-90 and a 45-45-90 triangle?
A 30-60-90 triangle has sides in the ratio 1 : √3 : 2, so the side opposite 30° is half the hypotenuse; a hypotenuse of 10 gives legs of 5 and 8.6603. A 45-45-90 triangle has equal legs and a hypotenuse √2 ≈ 1.4142 times a leg, so legs of 7 give a hypotenuse of 9.8995.
What does SOHCAHTOA mean?
It is a memory aid for the three trigonometric ratios in a right triangle: sine = opposite/hypotenuse, cosine = adjacent/hypotenuse, tangent = opposite/adjacent. In the 3-4-5 triangle, the angle opposite the side of 3 has sin = 0.6, cos = 0.8 and tan = 0.75, and each inverse function returns the same 36.87°.
How do you check a corner is square with the 3-4-5 rule?
Mark 3 units along one side and 4 along the other, measured from the corner; the diagonal between the marks is exactly 5 when the angle is 90°. A longer diagonal means the angle is too wide: 5.05 m on 3 m and 4 m legs is 91.2°, and 4.95 m is 88.8°. Multiples such as 6-8-10 or 9-12-15 give a more precise check on large slabs.