Math Problem Statement

Solve these questions

Solve the following right-angled triangles and trigonometric equations provided in the image.

Solution

Let's begin by solving the problems listed in the image.

Part 1: Trigonometric Equations

i. 2sin2θ=122\sin^2\theta = \frac{1}{2}

To solve for θ\theta:

  1. Divide both sides by 2: sin2θ=14\sin^2\theta = \frac{1}{4}
  2. Take the square root of both sides: sinθ=±12\sin\theta = \pm \frac{1}{2}
  3. Solving for θ\theta: θ=30,150(for sinθ=12)\theta = 30^\circ, 150^\circ \quad (\text{for } \sin\theta = \frac{1}{2}) θ=210,330(for sinθ=12)\theta = 210^\circ, 330^\circ \quad (\text{for } \sin\theta = -\frac{1}{2})

ii. sinθ=cosθ\sin\theta = \cos\theta

We know that: sinθ=cosθ    tanθ=1\sin\theta = \cos\theta \implies \tan\theta = 1 Thus, θ=45\theta = 45^\circ, and for general solutions: θ=45+180n,nZ\theta = 45^\circ + 180^\circ n, \quad n \in \mathbb{Z}

Part 2: Solving Right-Angled Triangles

Now, let's proceed with solving the right-angled triangles.

i. ΔABC\Delta ABC, C=90\angle C = 90^\circ, a=4cm,c=42cma = 4 \, \text{cm}, \, c = 4\sqrt{2} \, \text{cm}

We will use the Pythagorean theorem to find side bb: c2=a2+b2c^2 = a^2 + b^2 (42)2=42+b2    32=16+b2    b2=16    b=4cm(4\sqrt{2})^2 = 4^2 + b^2 \quad \implies \quad 32 = 16 + b^2 \quad \implies \quad b^2 = 16 \quad \implies \quad b = 4 \, \text{cm}

ii. ΔPQR\Delta PQR, Q=90,P=60,PQ=43cm\angle Q = 90^\circ, \, \angle P = 60^\circ, \, PQ = 4\sqrt{3} \, \text{cm}

Since we have one angle and one side, we can use trigonometric ratios to solve for the other sides: sin60=QRPQ    QR=PQ×sin60=43×32=6cm\sin 60^\circ = \frac{QR}{PQ} \quad \implies \quad QR = PQ \times \sin 60^\circ = 4\sqrt{3} \times \frac{\sqrt{3}}{2} = 6 \, \text{cm} cos60=PRPQ    PR=PQ×cos60=43×12=23cm\cos 60^\circ = \frac{PR}{PQ} \quad \implies \quad PR = PQ \times \cos 60^\circ = 4\sqrt{3} \times \frac{1}{2} = 2\sqrt{3} \, \text{cm}

iii. ΔPQR\Delta PQR, R=90,PR=8m,RQ=8m\angle R = 90^\circ, \, PR = 8 \, \text{m}, \, RQ = 8 \, \text{m}

This is an isosceles right triangle, so PQPQ can be calculated using: PQ=PR×2=82mPQ = PR \times \sqrt{2} = 8\sqrt{2} \, \text{m}

iv. ΔXYZ\Delta XYZ, X=90,YZ=16m,XZ=8m\angle X = 90^\circ, \, YZ = 16 \, \text{m}, \, XZ = 8 \, \text{m}

Using the Pythagorean theorem: YZ2=XY2+XZ2    162=XY2+82    256=XY2+64    XY2=192YZ^2 = XY^2 + XZ^2 \quad \implies \quad 16^2 = XY^2 + 8^2 \quad \implies \quad 256 = XY^2 + 64 \quad \implies \quad XY^2 = 192 XY=192=83mXY = \sqrt{192} = 8\sqrt{3} \, \text{m}

v. ΔLMN\Delta LMN, LM=10cm,MN=8cm,NL=6cmLM = 10 \, \text{cm}, \, MN = 8 \, \text{cm}, \, NL = 6 \, \text{cm}

Since all three sides are given, we can verify if it's a right triangle by checking the Pythagorean theorem: LM2=MN2+NL2    102=82+62    100=64+36LM^2 = MN^2 + NL^2 \quad \implies \quad 10^2 = 8^2 + 6^2 \quad \implies \quad 100 = 64 + 36 This is a valid right triangle.

Would you like further details on any of these solutions, or have any questions about the process?

Here are 5 related questions for further exploration:

  1. How can we generalize solutions for trigonometric equations like sin2θ=k\sin^2 \theta = k?
  2. What is the method to find the area of right-angled triangles?
  3. How can we apply the sine and cosine rules to non-right-angled triangles?
  4. What are the steps for solving triangles using the tangent function?
  5. How does the Pythagorean theorem extend to 3D geometry?

Tip: When solving trigonometric equations, always check for all possible solutions within the given range of angles.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Trigonometry
Pythagorean Theorem
Trigonometric Equations

Formulas

Pythagorean Theorem: a^2 + b^2 = c^2
Sine: sin θ = opposite/hypotenuse
Cosine: cos θ = adjacent/hypotenuse
Tangent: tan θ = opposite/adjacent

Theorems

Pythagorean Theorem
Trigonometric Identities

Suitable Grade Level

Grades 10-12