Mathematics
Grade 10
15 min
Solve a right triangle
Solve a right triangle
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Identify the hypotenuse, opposite, and adjacent sides relative to a given acute angle in a right triangle.
Apply the primary trigonometric ratios (SOH CAH TOA) to find the length of a missing side.
Use inverse trigonometric functions (sin⁻¹, cos⁻¹, tan⁻¹) to find the measure of a missing angle.
Apply the Pythagorean theorem to find a missing side length when two sides are known.
Solve a right triangle completely by finding all unknown side lengths and angle measures.
Model and solve real-world problems involving right triangles.
Ever wondered how engineers determine the height of a skyscraper or how a ship navigates the sea? 🏙️ It all starts with a simple shape: the right triangle!
In this tutorial, you will learn how to 'solve a right triangle,...
2
Key Concepts & Vocabulary
TermDefinitionExample
Solving a Right TriangleThe process of finding the measures of all three sides and all three angles of a right triangle, given some initial information (like two sides, or one side and one acute angle).If you know one leg is 3 cm, the hypotenuse is 5 cm, and one angle is 90°, you would solve for the third side (4 cm) and the other two angles (approx. 36.9° and 53.1°).
Hypotenuse, Opposite, AdjacentThe names of the sides of a right triangle relative to a specific acute angle (θ). The Hypotenuse is always opposite the right angle. The Opposite side is across from angle θ. The Adjacent side is next to angle θ.In a triangle with angle A, the side across from A is 'opposite', the side next to A (that isn't the hypotenuse) is 'adjacent'.
Trigonomet...
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Core Formulas
The Trigonometric Ratios (SOH CAH TOA)
sin(θ) = \frac{Opposite}{Hypotenuse} \\ cos(θ) = \frac{Adjacent}{Hypotenuse} \\ tan(θ) = \frac{Opposite}{Adjacent}
Use these ratios to find a missing side when you know one side and one acute angle. Choose the ratio that connects the angle you know, the side you know, and the side you need to find.
The Pythagorean Theorem
a² + b² = c²
Use this theorem to find the length of a third side of a right triangle when you know the lengths of the other two sides. 'a' and 'b' are the legs, and 'c' is the hypotenuse.
Sum of Angles in a Triangle
∠A + ∠B + ∠C = 180°
In any triangle, the three interior angles add up to 180°. In a right triangle, since one angle is 90°, the two acute angles must add up to 90°.
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Sign Up Free to ContinueSample Practice Questions
Easy
In a right triangle ΔXYZ with the right angle at Y, which side is the 'opposite' side with respect to angle Z?
A.Side YZ (the side adjacent to ∠Z)
B.Side XY (the side across from ∠Z)
C.Side XZ (the hypotenuse)
D.Side YX (the side adjacent to ∠X)
Easy
In right triangle ABC with ∠C = 90°, if you know the length of the side adjacent to angle A and the length of the hypotenuse, which trigonometric ratio should you use to find angle A?
A.Cosine (Adjacent/Hypotenuse)
B.Sine (Opposite/Hypotenuse)
C.Tangent (Opposite/Adjacent)
D.Pythagorean Theorem
Easy
In a right triangle, one acute angle measures 42°. What is the measure of the other acute angle?
A.42°
B.58°
C.48°
D.138°
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