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How do you solve problems?
LEARNING
STANDARDS
4 Solve problems
involving triangles.
In the diagram, PQRS is a T
straight line. Calculate the
values of x and y. y 46°
x 84°
P Q R S

∠RST + 84° + 46° = 180° Sum of the interior angles of ∆RST. id ou now

∠ RST = 180° – 84° – 46° The symbol ∆ is used
to denote a triangle.
= 50°
Angles at the base of
∠ TQS = 50° an isosceles triangle.

x + 50° = 180° Sum of the interior angle and
its adjacent exterior angle.
x = 180° – 50°
= 130°
∠QTS + 50° + 50° = 180° Sum of the interior angles of ∆QST.

∠ QTS = 180° – 50° – 50°
= 80°
y + 46 = 80 o
o
y = 80° – 46°
CHAPTER
9
= 34°
Self Practice 9.2c

1. In the diagram, PSR is a straight line. Calculate P
the values of x and y. x
S
68°
Q y 24° R

2. In the diagram, PQR is a straight line. Calculate P
the values of x and y. y
118°
Q

x

R

210
Chapter 9

09 TB Math F1.indd 210 11/10/16 12:18 PM