Back to Prove theorems about lines — Problem 4 · Task Set 9

Exercises: Prove Theorems About Lines and Angles

Work through each section in order. For proof problems, show each step with its justification. Express angle measures in degrees.

Grade 9·21 problems·~35 min·Common Core Math - HS Geometry·standard·hsg-co-c-9

Work through problems with immediate feedback

Fluency Practice

Apply the theorems directly. Identify angle relationships and find missing measures.

Line $l \parallel$ line $m$ , cut by transversal $t$ . $\angle 1 = 115^\circ$ (at line $l$ , upper-left position). What is the measure of the corresponding angle at line $m$ ?

$65^\circ$

$115^\circ$

$90^\circ$

$180^\circ$