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Course: Digital SAT Math>Unit 13

Lesson 3: Right triangle trigonometry: advanced

Right triangle trigonometry — Basic example

Watch Sal work through a basic Right triangle trigonometry problem.

Want to join the conversation?

• Are we allowed to draw visual aid on the SAT test?
• Pretty sure you can draw on the booklet with the problems on it. Not the answer sheet though.
• Wouldn't it be easier (at ) to prove that quadrilateral ACDB is a parallelogram?
Since the sides are parallel it is easy to prove and then you know that the opposite angles are congruent.
• the law of sine and cosine formula is another way to solve it
• No, they can only be applied in non-right angle triangles
• All I did was cos(70) = x / 8.9 and I got the right answer. Did I simply get lucky or did I actually solve it correctly?
• Yes that is the correct beginning. To isolate for x, you multiply both sides by 8.9, so
x = 8.9 ∙ cos(70)
x ≈ 8.9 (0.342)
x ≈ 3.04
Of course you need to know from geometry that `the side you solved for will be congruent to the side they are asking for`. About half the video seems to be about proving that CD ≅ AB, the side they are asking for, by proving that the two triangles are congruent and that those two sides are corresponding sides of the two triangles.
• in which sections are we allowed to use a calculator
• There are two math sections, the first one is 20 questions and you will not be able to use the calculator, the second section is devised of 38 questions and you will be able to use a calculator. Just for reference the first section is mostly just math theory, so if you know the basic principles taught in Pre-Algebra, Algebra 1 and 2, and some geometry you shouldn't need a calculator. Hope this helps!
• Hi guys...do we have a Nigerian in the house...I feel pretty lonely here...?
• better than SOH CAH TOA

remember this sentence

*S*ome People Have *C*urly Brown Hair *T*hrough Proper Brushing.

Sine=S=P/H
COSINE=C=B/H
TAN=T=P/B

> P=Perpendicular
B=Base
H=Hypotenuse