Math Problem Statement

find correct to the nearest degree the three angles of the triangle with the given vertices. P(2,0), Q(0,3), R(3,4)

Solution

To find the angles of the triangle with the vertices P(2,0)P(2, 0), Q(0,3)Q(0, 3), and R(3,4)R(3, 4), we can follow these steps:

Step 1: Find the lengths of the sides

We use the distance formula to find the lengths of the sides of the triangle. The distance between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is given by:

d=(x2x1)2+(y2y1)2d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}

Side PQPQ (between points P(2,0)P(2, 0) and Q(0,3)Q(0, 3)):

PQ=(02)2+(30)2=(2)2+(3)2=4+9=133.61PQ = \sqrt{(0 - 2)^2 + (3 - 0)^2} = \sqrt{(-2)^2 + (3)^2} = \sqrt{4 + 9} = \sqrt{13} \approx 3.61

Side PRPR (between points P(2,0)P(2, 0) and R(3,4)R(3, 4)):

PR=(32)2+(40)2=(1)2+(4)2=1+16=174.12PR = \sqrt{(3 - 2)^2 + (4 - 0)^2} = \sqrt{(1)^2 + (4)^2} = \sqrt{1 + 16} = \sqrt{17} \approx 4.12

Side QRQR (between points Q(0,3)Q(0, 3) and R(3,4)R(3, 4)):

QR=(30)2+(43)2=(3)2+(1)2=9+1=103.16QR = \sqrt{(3 - 0)^2 + (4 - 3)^2} = \sqrt{(3)^2 + (1)^2} = \sqrt{9 + 1} = \sqrt{10} \approx 3.16

Step 2: Use the Law of Cosines to find the angles

The Law of Cosines states: cosC=a2+b2c22ab\cos C = \frac{a^2 + b^2 - c^2}{2ab} Where aa, bb, and cc are the lengths of the sides, and CC is the angle opposite side cc.

We will use this formula to find each of the angles.

Angle PQR\angle PQR (opposite side PRPR):

cosPQR=PQ2+QR2PR22PQQR\cos \angle PQR = \frac{PQ^2 + QR^2 - PR^2}{2 \cdot PQ \cdot QR} Substituting the values: [ \cos \angle PQR = \frac{(3.61)^2 + (3.16)^2 - (4.12)^2}{2 \cdot 3.61 \cdot 3.16} = \frac{13.0321 + 9.9856 - 16.9744}{

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Math Problem Analysis

Mathematical Concepts

Geometry
Triangle
Distance Formula
Law of Cosines

Formulas

Distance Formula: d = sqrt((x2 - x1)^2 + (y2 - y1)^2)
Law of Cosines: cos(C) = (a^2 + b^2 - c^2) / (2ab)

Theorems

Law of Cosines

Suitable Grade Level

Grades 9-12