How to find the adjacent side of a triangle calculator

Our online tools will provide quick answers to your calculation and conversion needs. On this page, you can solve math problems involving right triangles. You can calculate angle, side (adjacent, opposite, hypotenuse) and area of any right-angled triangle and use it in real world to find height and distances.

Download: Use this right-triangle solver offline with our all-in-one calculator app for Android and iOS.

Right triangle calculation

Formulas used for calculations on this page:

Pythagoras' Theorem
a2 + b2 = c2

Trigonometric functions:
sin(A) = a/c, cos(A) = b/c, tan(A) = a/b
sin(B) = b/c, cos(B) = a/c, tan(B) = b/a

Area = a*b/2, where a is height and b is base of the right triangle.

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a=3 b=4 c=5 ... triangle calc by three sides a,b,c.
B=45 c=10 a=9 ... triangle calc by two sides a,c and included angle B.
A=25 C=80 b=22
A=35 C=26 a=10
a=3 C=90 c=5 ... how to enter right-angled triangle.
a=3 β=25 γ=45 ... triangle calc if we know the side and two angles.
a=3 β=25 T=12 ... triangle calc, if know side, angle, and area of a triangle.
T=2.5 c=2 b=4 ... find side a if know sides b, c, and area of triangle T.
ma=1 b=2.5 c=2 ... calculation of the triangle if we know one median and any two sides.
ma=1 mb=2.5 mc=2 ... triangle calc by three medians.
ha=220, hb=165 hc=132 ... triangle calc by three heights.
a=7 β=40 mc=5 ... triangle calc by one side, one angle, and one median.
a:b:c=2:3:4 T=2.5 ... a triangle where the known side ratio, and its area.
A:B:C=1:4:5 a=2 ... calculating triangle if we know the ratio of the internal angles and one side.

What do the symbols mean?
a, b, c ... sides BC, AC, AB
A, B, C or α, β, γ  ... internal angles
ha, hb, hc ... heights
ma, mb, mc ... medians
T ... area
p ... perimeter
s ... semiperimeter

Angle and adjacent of right triangle

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Disp-Num

[1]  2018/05/20 16:17   50 years old level / An office worker / A public employee / Very /

[2]  2017/07/02 17:31   50 years old level / High-school/ University/ Grad student / Very /

[3]  2017/05/10 18:48   Under 20 years old / High-school/ University/ Grad student / A little /

[4]  2015/02/23 16:37   50 years old level / A teacher / A researcher / Not at All /

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Adjacent and opposite of right triangle

[1-10] /13

Disp-Num

[1]  2021/11/30 19:04   Under 20 years old / Elementary school/ Junior high-school student / Useful /

[2]  2021/10/01 06:45   50 years old level / An engineer / Very /

[3]  2021/07/27 20:50   Under 20 years old / Elementary school/ Junior high-school student / Very /

[4]  2021/02/28 17:42   50 years old level / An engineer / Very /

[5]  2021/01/31 19:18   50 years old level / An engineer / Very /

[6]  2020/07/08 14:57   40 years old level / High-school/ University/ Grad student / Very /

[7]  2020/04/28 01:06   50 years old level / Self-employed people / Very /

[8]  2019/12/28 22:56   60 years old level or over / An office worker / A public employee / Very /

[9]  2019/06/20 12:12   50 years old level / An office worker / A public employee / Very /

[10]  2010/03/22 12:28   40 level / Others / Very /

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How do you find adjacent angles in a triangle?