Question 276·Easy·Math

0 / 2000

In $\triangle ABC$ , the measure of angle $A$ is $50^\circ$ and the measure of angle $B$ is $60^\circ$ . What is the measure of angle $C$ ?

Two known angles inside a triangle cue the triangle angle-sum theorem: all three interior angles total $180^\circ$ . Label the missing angle and write an equation using that total. You can solve the equation in Desmos with a regression using $x_1$ and $\sim$ . The tempting trap is to add the known angles and stop; that gives the part of the total already accounted for.

Hints

Hint 1
An interior angle is an angle inside the triangle. The three interior angles add to $180^\circ$ , so include the unknown angle at $C$ when you write the equation.
Hint 2
The known angles account for part of the total, not the angle you need. What value would make their sum with angle $C$ equal $180^\circ$ ?

Step-by-step

Use the triangle angle sum
Step 1
Write the angle equation
The angles at $A$ , $B$ , and $C$ are interior angles, the angles inside the triangle. All three interior angles add to $180^\circ$ , so if $c$ is the measure of angle $C$ in degrees, write:
$50+60+c=180.$
Step 2
Find the missing angle
Type $50+60+x_1\sim180$ in Desmos. Here $x_1$ stands for $c$ , and $\sim$ asks Desmos to find the value that makes both sides equal. Under PARAMETERS, Desmos shows $x_1=70$ . So the angle at $C$ measures $70^\circ$ . Choice C.

Lessons that teach this

SAT Geometry and TrigonometryIntermediateCoreUse triangle angle theorems

Question 276·Easy·Math

Strategy

Hints

Step-by-step

Lessons that teach this

Study Hints

Strategy

Hints

Step-by-step

Lessons that teach this