McGraw Hill Integrated II, 2012
MH
McGraw Hill Integrated II, 2012 View details
1. Angles of Triangles
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Exercise 39 Page 341

Introduce a variable for the measure of the smaller acute angle.

Smaller angle: 23^(∘)
Larger angle: 67^(∘)

Practice makes perfect

The exercise reads like a riddle. We will break it down into steps. First, Let's introduce a variable x for the measure of the smaller acute angle. We can then use the information given to write an expression for the measure of the larger acute angle in terms of this variable x.

Information Expression
This is the variable we chose to be the measure of the smaller acute angle. x
The measure of the larger acute angle is two degrees less than three times the measure of the smaller acute angle x. 3x - 2
Additionally, it is given that these are acute angles of a right triangle. According to Corollary 4.1 of the Triangle Angle-Sum Theorem, the acute angles of a right triangle are complementary, so their measures add to 90^(∘). We can use this to set up and solve an equation for x.
x+(3x-2)=90
Solve for x
x+3x-2=90
4x-2=90
4x=92
x=23
Using this value and the expressions, we can find the measure of the acute angles of the triangle.
Angle Expression Angle Measure
Smaller acute angle. x 23^(∘)
Larger acute angle. 3x-2 3(23)-2=67^(∘)